REPORT ON THE HETEROPODA. 
21 
gelatinous points ” were in reality tentacles. This opinion is strengthened by the fact 
that the presence of denticles in front of the eyes, which are so usual in species of 
Pterotrachea, have not since been observed in any form of Firoloida. 
D’Orbigny was the next to describe two animals belonging to this genus, which he 
named Firola ( Cerophora ) gaimardii and Firola ( Cerophora ) lesueurii. The figures 
of these two so-called species, which were considered (probably correctly) identical by 
Souleyet, appear to be rather fanciful, judging by the more accurate illustrations of 
Eydoux and Souleyet and Macdonald, and an examination of the Challenger and other 
specimens, both Firoloida gaimardii and Firoloida lesueurii exhibit tentacles and doubt- 
less were males. 
Souleyet in the Voyage of the “ Bonite ” next described an animal which he identified 
with the Firoloida desmarestii of Lesueur. This also was a female without tentacles. 
He also described and figured a second example under the name Firoloida lesueurii , 
which was a male and provided with tentacles. 
In 1855 Troschel characterised two new species which he believed to represent a new 
genus, and which he styled Firolella, considering it distinct from Firoloida in having 
no tentacles. It seems to me certain that he never consulted Lesueur s account of 
that genus, but must have based his opinion upon the writings of d’Orbigny and 
Souleyet. Lesueur distinctly mentions the absence of tentacles in his diagnosis of the 
genus. 
The first of Troschel’s species, Firolella gracilis, was a female, the second, Firolella 
vigilans, he supposed to be a male. In the latter I should have expected the presence 
of tentacles, but according to Troschel none existed. Their absence, I think, might 
possibly be due to the very young state of the animal, which was less than a quarter of 
an inch in length. They might not have been develojDed in an animal apparently so 
young, 1 or even have escaped observation on account of their minuteness. 
The next representation of a species of Firoloida is that given by Macdonald, who 
describes and figures a male with tentacles and a sucker on the ventral Jin, a feature not 
previously noted. Fewkes has since recorded the presence of a fin-sucker in females of 
Firoloida lesueurii. In the Challenger specimens and others which I have examined 
belonging to this genus, the males only have this organ, and also possess tentacles, the 
females on the contrary being destitute of both. 
From these remarks it will be observed that the presence or absence of tentacles is 
presumed to be a sexual and not a specific or generic character. 
Formerly the possession or want of a sucker on the fin was regarded as indicative of 
sex in the species of Pterotrachea, and a similar result might have been expected with 
regard to Firoloida. In both instances, however, it has been demonstrated by Paneth 
and Fewkes that the presence or absence of this character is not constant in either 
1 Krohn also regards this as a very young, recently metamorphosed, example of a Firoloida or Pterotrachea. 
