22 
THE VOYAGE OF H.M.S. CHALLENGER. 
males or females ; but it has been noticed by the former that the sucker was usually 
smaller in female specimens than in males. 
After studying the various figures and descriptions of Firoloida which have been 
published, I have not been able to arrive at any satisfactory or definite opinion with 
regard to the value of the species. Whether they will eventually all resolve themselves 
into one or two variable forms, or how many distinct species they constitute, is 
uncertain. In order to arrive at a definite decision it would be necessary to have a 
much larger series of specimens from various localities for examination than I have had 
the opportunity of studying. I think then it will be the safest course to leave this 
question unsettled, and also not to attempt to decide which of the figured males and 
females should be associated together. 
I might, however, point out that Macdonald has erroneously stated that Firoloida 
desmarestia is the female of Pterotrachea Jceraudrenii. The latter has a rather unusual 
form for a Pterotrachea, but still I believe it belongs to that genus, as it has a caudal 
prolongation, the nucleus being far from terminal, and no tentacles, the latter, if my 
surmise be correct, being an essential characteristic of the males of Firoloida, their 
absence, therefore, clearly showing that the animal in question was not the male of 
Firoloida desmarestia. 
Firoloida desmaresti, Lesueur. 
1817. Firoloida desmarestia, Lesueur, Journ. Acad. Nat. Sci. Philad., vol. i. p. 39, pi. ii. figs. 1, 15, 
1817. ,, „ id., Bull. Soc. Philom. Paris, p. 160. 
1818. Firloides desmarestia, Oken, Isis, p. 1559. 
1820. Firoloida desmarestia, Blainville, Diet. d. Sci. Nat., vol. xvii. p. 68. 
1825. Pterotrachea ( Firoloida ) desmarestiana, id., Blainville, Man. Malacol., p. 492. 
1850. „ „ desmarestia, Gray, Fig. Moll. Anim., pi. civ. fig. 8 (copy of 
Lesueur). 
1850. „ „ „ id., op. cit., pi. ccxxxviii. fig. 1 (copy of Eydoux 
and Souleyet). 
1850 1 Firoloides desmaresti, Deshayes, Traite Conch., pi. cii. fig. 4 (copy of Eydoux and Souleyet). 
1852. Firoloida desmarestia, Eydoux et Souleyet, Voy. “ Bonite,” Zool., vol. ii. p. 342, pi. xvi. 
figs. 1-4. 
1853. Firloides desmarestii, Huxley, Phil. Trans., vol. cxliii. pp. 30-36, pi. ii. figs. 1-8, 
(Anatomy). 
1855. Firoloides desmarestii, Gegenbaur, Untersuch. Pterop. und Heterop., p. 215. 
1855. Pterotrachea desmarestina, H. and A. Adams, Gen. Moll., vol. ii. p. 94. 
1856. Firoloides desmarestii , Troschel, Gebiss d. Schneck., vol. i. p. 45. 
1876. ,, desmaresti, Fol, Arch. d. Zool. Exper., vol. v. p. 105, pis. i., ii., iii. 
(Development). 
Habitat. — Atlantic, near Martinique (Lesueur); Atlantic and Pacific Oceans (Eydoux 
and Souleyet). 
