TETHYS. H# 



Aplysia nigromarginata Risso, t. c., p. 375, and Hist. Nat. Eur. 

 Merid., iv, p. 43. 



Aplysia lutea Risso, J. Phys., p. 375, and Hist. Nat., p. 43. 



All described from the vicinity of Nice, and none of them recog- 

 nizable with certainty. 



Aplysia unicolor Blainville, Diet. Sc. Nat., xxvi, p. 327 (1823) ; 

 Journ. de Phys., Vol. 96, f. 9, 10. Bayonne, Toulon, Ocean coast 

 of France. Not recognizably described. 



Aplysia petersonii Gray. Body contracted posteriorly, and 

 divided transversely into two portions. Head very large, depressed 

 smooth. Foot very broad, deeply emarginate in front, expanded 

 beyond the edge of the body ; the part beneath the hinder portion 

 of the body divided by deep wrinkles into distinct tubercles. Mouth 

 sunk in, large; labial expansions short, triangular, wrinkled. Ten- 

 tacula situated half way between the head and the transverse con- 

 traction, short > conical. Body subglobular, externally tubercular, 

 wrinkled. Lobes of the mantle rounded, united behind, the right 

 one rather longer than the left, partly covering the shield. Shield 

 partly exposed, ovate; nucleus submedial ; columellar edge sub- 

 angularly bent. Length 5 inches, breadth 2 inches. (Gray.*) 



This species constitutes a peculiar section of the genus, character- 

 ized by the transverse contraction of the body. The animal figured 

 in Seba, iii, t. 1, f. 8, 9 (Aplysia sebce, n.) appears to belong to the 

 same section. It differs from the foregoing species in the form of 

 the hinder part of the foot, etc. (Gray Spicilegia Zoologica, pt. I, 

 p. 4, pi. 4, f. 4, 4a (one-half nat. size). July }, 1828.) 



Marseilles (Peterson esq.). 



I am disposed to think this a peculiarly abnormal specimen of 

 Tethys leporina. It was evidently described from an alcoholic exam- 

 ple. Type said to be in Brit. Mus. So werby's later A. petersoni (see 

 p. 70) is not the same. 



Aplysia sebce Gray, Spicil. Zool., p. 5 ; Seba, Locupletissimi Rerum 

 Naturalium Thesauri, etc., iii, p. 4, pi. 1, f. 8, 9. Gray's informa- 

 tion on this is contained in the last paragraph of his description of 

 A. petersoni (see above). On referring to Seba's portly folio I am 

 quite ready to endorse his opinion that the creature pictured is a very 

 singular marine monster; but my Aplysia lore does not enable me 

 to name it. 

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