166 echinoiuea. ii. 



(or elongate), 1 the confusion of this species with lyrifera having caused the erroneous statement of the 

 development of the petals. — It is also a curious fact that in the Blake -Ech. p. 70 Agassiz speaks 

 of the confluent ambulacra as an «embryological character .-, in direct opposition to the above citations, 

 where this character is said to be developed with age. 



The subanal fasciole is also said ( Rev. of Ech. loc. cit.) to be subject to very great changes, 

 due to different stages of growth; in the Blake -Echinoidea it is even stated to have disappeared 

 completely in some specimens, viz. in the globular specimens from off Missisippi. That none of these 

 globular specimens are really Br. lyrifera, I think beyond doubt; they will probably turn out to be 

 partly Br. alia and partly, viz. those without a subanal fasciole, Periaster limicola. (To be sure, I have 

 not myself seen any specimens of Periaster limicola identified as '.Brissopsis lyrifera , but I have seen 

 specimens of Brissopsis «lyrifera» (alia) identified as Periaster limicola (comp. above p. 159), so it may 

 not seem very hazardous to suggest that the reverse case may also be found). Until by a renewed 

 examination of these globular specimens without a subanal fasciole it is shown definitely to which 

 species they belong, I must doubt that they belong to the genus Brissopsis. So far as my experience 

 goes — and I have examined a considerable number of specimens, especially of the species lyrifera 

 and luzonica — the subanal fasciole is very constant in this genus, as upon the whole this fasciole is 

 one of the most constant features in the Amphisternous Spatangoids. That it may, however, sometimes 

 really disappear I have shown above (p. 129) for Spatangus Raschi. — On the other hand there is really 

 considerable variation in the anal branch, the small fasciole running from the subanal fasciole along 

 the sides of the anal area straight towards the peripetalous fasciole in the Brissopsis-species , as 

 pointed out by Agassiz. But this fasciole must, of course, not be confounded with the subanal fasciole. 

 In the true Br. lyrifera the anal branch is very seldom developed; only in a single specimen (Tngolf» 

 St. 6) they were both distinctly developed, reaching the peripetalous fasciole; in a very few instances 

 I have found slight traces thereof. 



In the < Panamic Deep Sea Echini > (p. 193) Professor Agassiz maintains the old genus Toxo- 

 brissus Desor, pointing out the following characters as distinguishing it from Brissopsis: The genital 

 plates of Toxobrissus do not extend into the interambulacral areas, which the}- do in Brissopsis. The 

 extremities of five ambulacral plates are included in the <anal (viz. subanal) fasciole of Toxobrissus, 

 whereas only four are so included in Brissopsis. The labrum of Brissopsis is shorter and more T-shaped 

 than in Toxobrissus. Further «the arrangement of the apical interambulacral plates of the odd inter- 

 ambulacrum shows at once the radical difference existing between Toxobrissus and Brissopsis . The 

 confluence of the posterior petals is not recognised as a character of the genus Toxobrissus. 

 the West Indian specimens of < Brissopsis lyrifera-* with confluent ambulacra being expressly stated not 

 to belong to the genus Toxobrissus (p. 191. Note); on the other hand it is said (p. 193) after pointing 

 out the characters mentioned above as distinguishing Toxobrissus and Brissopsis - «that we are 



1 Bittner (Uber Parabrissus und einige andere alttertiare Eehiniden-Gattungen. Verhandl. d. K. K. geol. Reichs- 

 anstalt. 1891. p. 137) lias already suggested that these figures do not represent one and the same species — eine Umwand- 

 lung von Taf. XIX. Fig. 8 dureh Taf. XIX. Fig. 9 in Taf. XXI. Fig. 2 anzunehmen, diirfte sehr gewagt sein>. Also Pomel has 

 perhaps seen that; in any case he says iClassif. meth. p. 33): <le pretendu Brissopsis lyrifera de la Floride est probablement 

 une autre espece vivante-, viz. of the genus K/einia, which he maintains as a separate genus. 



