Revision of the Genus Lomanotus. 217 



it iniglit just as well have developed into Trinchese's 

 L. eisigit, and so it must be dismissed as dubious. 



The obscurity in Thompson's description of the pleuro- 

 ]iodium in L. portlandicus has already been pointed out. 

 Whether the continuation of the pleuropodium '' behind the 

 termination of the taiP' points to any peculiarity of structure 

 similar to the caudal fin of I'rinchese^s species it is impossible 

 to decide in the absence of a figure. The form of the divisions 

 of its sheath-margin and the fact that they were six rather 

 than four or five in number are in themselves insufficient as 

 specific characters. 



Apart from the number of divisions in its sheath-margin, 

 the fourth British species, L. hancocki, is distinguished from 

 previously described species merely by the form of the 

 rhinophore, which is said to be non-laminate and scarcely 

 longer than the sheath. There can be little doubt that in 

 this case the rhinophores were examined when fully retracted, 

 so that the smooth tips alone were visible, and that a dissec- 

 tion, if it had been made, would have shown their upper 

 portions to possess the lamination characteristic of the genus. 



On the whole, then, it appears that none of the structural 

 features relied on as distinguishing the British species, 

 L. marmoratusj L. 'portlandicus^ and h. hancocki^ from the 

 Mediterranean species, Li. genei, possesses the necessary 

 certainty and constancy ; and since colourper.se cannot afford 

 any valid specific character, the reduction to one of these four 

 species appears to be fully justified. 



So far it is easy to follow Mr. Garstang in his proposed 

 fusion of the six species of Lomanotus. It is not possible, 

 however, to go farther with him and sink Trinchese's L. eisigii. 

 The peculiar modification of its pleuropodium, whose character 

 and development are so well described by the Italian scientist, 

 tully entitles this form to specific rank and decisively forbids 

 its fusion with the others. 



To sum up, it is submitted that the evidence adduced in 

 the historical survey just given warrants the reduction of the 

 six species of the genus to the two species set out below, 

 L.Jlavidus being dismissed as doubtful. 



Lomanotus, Verany, Revue Zoologique par la Soci^t^ 

 Cuvierienne, tome vii. p. '60iS (1844). 



L. marmoratus, Alder and Hancock, Ann. & Mag. Nat. Hist. 

 vol. xvi. p. 311 (1845). 



L. genei, Verany, Catal. degii Animali invert, marini del Ciolfo di 

 Genova e Nizza (1840). 



Ann. & Miig. N. Hist. Scr. 8. Vol. ii. 15 



