His most important anthropological work was his description of sixty human crania published originally in fasciculi under the title Collectionis suae craniorum diversarum gentium illustratae decades (Gottingen, 1790-1828).
Other forms show no indication of ever having been attached, while some that had been moored by means of a peduncle during the early portion of their existence have become detached at a more advanced stage of life, the opening becoming gradually cicatrized, as is so often seen in Leptaena rhomboidalis, Orthisina anomala, &c. Lastly, some species adhere to submarine objects by a larger or smaller portion of their ventral valve, as is the case with many forms of Crania, Thecidium, Davidsonia, &c. Some Cranias are always attached by the whole surface of their lower or ventral valve, which models itself and fills up all the projections or depressions existing on either the rock, shell or coral to which it adhered.
These often have the form of prisms of calcite surrounded by a cuti cular meshwork; the whole is nourished and kept alive by processes, which in Crania are branched; these perforate the shell and permit the access of the coelomic fluid throughout its substance.
These spaces are as follows: - (i.) the great arm-sinus; (ii.) the small arm-sinus together with the central sinus and the peri-oesophageal sinus, and in Discinisca and Lingula, and, to a less extent, in Crania, the lip-sinus; (iii.) certain portions of the general body cavity which in Crania are separated off and contain muscles, &c.; (iv.) the cavity of the stalk when such exists.
In Crania it is completely shut off from the main coelom, but in Lingula it communicates freely with this cavity.
In Crania, where only indications of the lip-sinus occur, there are two other closed spaces.
In Lingula and Discina the anus lies to the right in the mantle-cavity, but in Crania it opens medianly into a posterior extension of the same.
Blochmann in 1884, however, observed this organ in the living animal in species of the following genera: - Terebratulina, Magellania [Waldheimia], Rhynchonella, Megathyris (Argiope), Lingula and Crania (fig.
Crania in life opens its valves by moving upon the straight hinge, without sliding the valve.
The above account applies more particularly to Crania, but in the main it is applicable to the other Inarticulata which have been investigated.
- Diagram of nervous system of Crania; from the dorsal side.
Wood, Cryptopora gnomon Jeff., Rhynchonella (Hemithyris) psittacea Gmel., Crania anomala Mull., and Discinisca atlantica King.
Undue stress is often laid on the fact that Lingula has come down to us apparently unchanged since Cambrian times, whilst Crania, and forms very closely resembling Discina and Rhynchonella, are found from the Ordovician strata onwards.
Their crania have a normal development; their cheek-bones are high; their noses prominent, with large nostrils; their lips straight; and they are marked by the absence of the auricular lobules.
Elsewhere in the United States fossilized bones, crania of a low order, association of human remains with those of fossil animals are not necessarily evidence of vast antiquity.
Bones of bulls and male calves, especially crania, were collected and formed into huge ox-like mummies.
The most important data bearing upon the first great period are given elsewhere in this work, and it is proposed to offer here a more general survey.5 To the prehistoric ages belong the palaeolithic and neolithic flints, from the distribution of which an attempt might be made to give a synthetic sketch of early Palestinian man.6 A burial cave at Gezer has revealed the existence of a race of slight build and stature, muscular, with elongated crania, and thick and heavy skull-bones.