Metasoma Sentence Examples
The tergites of this region and those of the following region, the metasoma, are fused to form a second or posterior carapace in Limulus, whilst remaining free in Scorpio.
Passing on now from the mesosoma we come in Scorpio to the metasoma of six segments, the first of which is broad whilst the rest are cylindrical.
The somites of the metasoma carry no parapodia.
In Limulus the metasoma is practically suppressed.
It is probable that we have in the metasoma of Limulus a case of the disappearance of once clearly demarcated somites.Advertisement
Perhaps the most important general agreement of Scorpio compared with Limulus and the Eurypterines is the division of the body into the three regions (or tagmata) - prosoma, mesosoma and metasoma - each consisting of six segments, the prosoma having leg-like appendages, the mesosoma having foliaceous appendages, and the metasoma being destitute of appendages.
The unsegmented dense chitinous sternal plate of the metasoma (XIII to XVIII) is not removed.
We shall, therefore, ignoring the ocular somite, speak of the first, second, third, fourth, fifth and sixth legbearing somites of the prosoma, and indicate the appendages by the Roman numerals, I, II, III, IV, V, VI, and whilst ignoring the praegenital somite we shall speak of the first, second, third, &c., somite of the mesosoma or opisthosoma (united mesosoma and metasoma) and indicate them by the Arabic numerals.
Intermediate somites forming a mesosoma occur, but tend to fuse superficially with the metasomatic carapace or to become co-ordinated with the somites of the metasoma, whether fused or distinct to form one region, the opisthosoma (abdomen of authors).
Concentration of the organ-systems by fusion of neighbouring regions (prosoma, mesosoma, metasoma), pre viously distinct, has frequently occurred, together with obliteration of the muscular and chitinous structures indicative of distinct somites.Advertisement
Not freeswimming, none of the prosomatic appendages modified to act as paddles; segments of the mesosoma and metasoma (= opisthosoma) not more than ten in number, distinct or coalesced.