584 TRITONIADiE. 



long filaments, the inner ones longest. Tentacles termin- 

 ating in a tuft of unequal laminated filaments, retractile 

 within sheaths which have scalloped margins. 



Taken by the authors of the " British Nudibranchiata," 

 and by Mr. Bean, under rocks at low water at Scar- 

 borough. 



SCYLL^A, LiNN^us. 



Body oblong or elongated, with compressed sides, a 

 convex back, and a linear foot. On each side of the back 

 are two large wing-like lobes bearing small ramose branchiae 

 on their inner surfaces. The tentacles are two, dorsal in 

 position, terminating in lamellated clubs, and retractile 

 within ample sheaths. The orifices are placed at the right 

 side. 



The animals of this genus are remarkable for being 

 the only nudibranchiate moUusks possessed of an armed 

 gizzard. They are oceanic, living on floating sea-weeds, 

 the stems of which they firmly clasp with the infolded 

 sides of their narrow crawling disk. Their anatomy has 

 been made the subject of elaborate investigation, formerly 

 by Cuvier, more recently by Alder and Hancock. 



S. PELAGicA, Linnaius. 



Plate A. A. A. fig. 5. 

 CuviER, Ann. du Museum, vol. vi. p. 416. 



We have never taken this animal in the British seas, 

 but it has been recently met with on the Devon coasts 

 (Alder). Mediterranean examples, which we have ex- 

 amined alive, were of a general tawny yellowish hue, and 

 fully an inch in length. 



