ANATOMY AND PHYSIOLOGY OF PATELLA VULGATA. 635 



present in some Patellidm, but denies that they occur in P. milgata; he more- 

 over thinks they are " aquiferous pores." The author's experience is that they 

 are present, and can be seen with the greatest of ease in all limpets ; that they 

 are, as described by Spengel (loc. cit), not " orifices" at all (and how they could 

 be called or thought so is to him a mystery), but rudiments of the lost true gills. 

 Gray, in his British Museum Catalogue, says that the milt or roe lies on the right 

 side ; the author's experience is that in the vast majority of cases it lies on the 

 left, although the point is of no great importance. 



Robin and Lebebt {Anal, de Sc. Nat., 1846) say that the generative gland 

 was wanting in more than half of the specimens they examined. Without 

 going so far as to contradict that statement, the writer must state that, in the 

 examination of over 100 specimens, he never found the generative glands 

 entirely wanting, although in some cases they were smaller in size. The 

 animals examined were collected in April, July, October, and December. The 

 writer found no indication whatever of any duct either from the testis or 

 ovary, and therefore is disposed to believe that the reproductive glands must 

 open at certain seasons into the right renal sac, and that they do not possess 

 special ducts of their own. 



EXPLANATION OF PLATES. 



PLATE CXLIX. 



Fig. 1. Patella vulgata, face view ( x 2). v.h., visceral hump; l.r.p. and r.r.p., left and right renal 

 papillae; a.p., anal papilla; cm., circular muscle; t., tentacle; m., mouth; /., foot. 



Fig. 2. Dorsal view, shell removed (n.s.). m.s., mantle skirt. 



Fig. 3. Dorsal view, visceral integument removed (n.s.). r., rectum ; pr., pericardium; ct., ctenidium; 

 I., liver; l.n., left nephridium ; r.n., right nephridium ; cm., circular muscle; ra., radula ; 

 s.i., superficial coil of the intestine; g., genital gland. 



Fig. 4. Visceral integument ( x 250). a, superficial pigmented epithelium ; b, median connective tissue 

 layer ; c, deep pigment layer (renal epithelium). 



Fig. 5. Superficial pigment layer of visceral integument ( x 500), surface view. 



Fig. 6. Epithelium over the circular muscle-hand ( x 250). a, ordinary cells ; b, transitional spindle- 

 shaped cells ; d, dense epithelium over the muscle, with cuticle ; c, muscle. 



Fig. 7. Deep epithelium of visceral integument, surface view ( x 500). 



Fig, 8. Epithelium covering the surface of the foot ( x 350). 



Fig. 9. Epithelium covering the head and neck ( x 500). 



Fig. 10. Transverse section of nuchal tentacle ( x 500). a, epithelium; b, nerve fibres; c, ventral 

 muscle band ; d, eye. 



Fig. 11. Longitudinal section of nuchal tentacle ( x 50). d, eye; e, pigment in subepithelial connective 

 tissue of tip of tentacle. 



Fig. 12. Epithelium of tentacle ( x 500). a, columnar cells; b, subcuticular layer of granular 

 proptoplasm ; c, cuticle ; d, trabeculae of connective tissue passing inward from g, the 

 subepithelial layer of connective tissue ; /, muscle fasciculi enclosed by connective tissue 

 cells, e. 



Fig. 13. Epithelium of tentacle on surface view ( x 500). 



