In the most primitive Lamellibranchs there is no separate generative aperture but the gonads discharge into the renal cavity, as in Patella among Gastropods.
The gill-lamellae of Patella are processes of the mantle comparable with the plait-like folds often observed on the roof of the branchial chamber in other Gastropoda (e.g.
This columella muscle is the same thing as the muscles adhering to the shell in Patella, and the posterior adductor of Lamellibranchs.
- Nervous system of Patella; the visceral loop is lightly shaded; the buccal ganglia are omitted.
9, 10) of _ the nervous systems of ` Patella and of Haliotis, e as determined by Spengel, show the identity in the origin of the nerves passing from the visceral loop to Spengel's olfactory ganglion of the fig..
In Colymbus the patella is reduced to a small ossicle, its function being taken by the greatly developed pyramidal processus tibialis anterior; in Podiceps and Hesperornis the patella itself is large and pyramidal.
- The Common Limpet (Patella vulgata) in its shell, seen from the pedal surface.
(d) Univalvia absque spira regulari: Patella, Dentalium, Serpula, Teredo, Sabella.
Patella had shown, in the Atti della R.
In these, as in Patella, the typical ctenidia are aborted, and the branchial function is assumed by close-set lamelliform processes arranged in a series beneath the mantle-skirt on either side of the foot.
4, d, the large branchial vein of Patella bringing blood from the gill-series to the heart is seen; where it crosses the series of lamellae there is a short interval devoid of lamellae.
The heart in Patella consists of a single auricle (not two as in Haliotis and Fissurella) and a ventricle; the former receives the blood from the branchial vein, the latter distributes it through a large aorta which soon leads into irregular blood-lacunae.
The existence of two renal organs in Patella, and their relation to the pericardium (a portion of the coelom), is important.
The digestive tract of Patella offers some interesting features.
The general structure of the Molluscan intestine has not been sufficiently investigated to render any comparison of this structure of Patella with that of other Mollusca possible.
Patella, pallial branchiae forming a complete circle, no epipodial tentacles, British.
1, The lamelliform sub-pallial gills, which (as in Patella) replace the typical Molluscan ctenidium.
Originally the Chitons were placed with the limpets, Patella, in Cuvier's Cyclobranchia, an order of the Gastropoda.
- Vertical section in a plane running right and left through the anterior part of the visceral hump of Patella to show the two renal organs and their openings into the pericardium.
- A, Section in a plane vertical to the surface of the neck of Patella through a, the rudimentary ctenidium (Lankester's organ), and b, the olfactory epithelium (osphradium); c, the olfactory (osphradial) ganglion.
(After Spengel.) B, Surface view of a rudimentary ctenidium of Patella excised and viewed as a transparent object.
There is a patella, intercalated in the tendon of the femori-tibialis or extensor cruris muscle.