324 Proceedings of the Royal Physical Society. 



any suckers with more than four well-developed teeth, and 

 my impression was that d'Orbigny's figure (pi. xxiii., figs. lU, 

 11) gave a much more accurate picture of the structure than 

 Dr de Kochebrune's. 



Leaciiia, Lesueur, 1821. 



Leachia, Lesueur, Steenstrup. 



Anisoctus {'i), Rafinesque. 



Loligopsis (pars), Gray, Tryon, de Rochebrune. 



Dictydiopsis, de Rochebrune. 



The genus Leachia w^as established by Lesueur in 1821 on 

 the basis of a drawing by Mr Petit representing an animal 

 captured in the Southern Ocean (Lesueur calls it "Pacific 

 Ocean," although the position given is lat. 37° S.,long. 33° E.). 

 It appears to have remained unused for forty years, until in 

 1861 Steenstrup reconstituted it and placed in it Loligopsis 

 ellipsoptera, Adams and Eeeve. 



Lesueur's diagnosis was short and quite insufficient for 

 modern requirements, though no doubt the distinctions he 

 drew were all that were required at the time he wrote. 



He says : " Eight unequal arms, the third pair longer and 

 more robust." 



Professor Steenstrup gives as the grounds for his recogni- 

 tion of the genus, as distinct from Taoniits and Cranchia, 

 three characters, — (1.) the absence of the tentacles, present 

 only as stumps ; (2.) the broad rounded fin ; (3.) two lines of 

 cartilaginous papillae down the ventral surface. 



That Lesueur overlooked the first and last of these points 

 is not strange, for, as we shall see further on, he had only a 

 drawing of the dorsal surface upon which to base his diagnosis. 



Adams and Eeeve have overlooked the stumps of the 

 tentacles and also the lines of papillae down the ventral 

 surface, in connection with which latter Steenstrup remarks : 

 " In consequence of the great transparency of the animal, 

 these lines are easily overlooked, and in the living animal 

 the difficulty of their recognition is naturally much increased. 

 It need not surprise us, therefore, that the figure of the Eng- 

 lish authors does not show them." ^ 



1 Overblik, p. 81 (13). 



