J.56 ECHINOIDEA. II. 



(or elongataY 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 oppcsition 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 

 completelv 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. alta and parti}-, viz. those without a subanal fasciole, Pcriaster Umicola. (To be sure, I ha\e 

 not myself seen any specimens of Periaster Umicola identified as <!,Brissopsis lyrifera ., but I have seen 

 specimens of Brissopsis iJyriferay> (alia) identified as Periaster Umicola (comp. above p. 159), so it may 

 not seem verv 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 definiteh- 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 Spatangoid.s. 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-s'^^Qx^s, as 

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

 In llic true Br. lyrifera the anal branch is very seldom developed; onh' in a single specimen («Ingolf» 

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

 I have found slight traces thereof. 



In tlie «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 they do in Brissopsis. The 

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

 wliereas 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 Brissopsiss. The 

 confluence of the posterior petals is not i-ecognised as a character of the genus Toxobrissus. 

 the West Indian specimens of i~ Brissopsis lyrifera» with confluent ambulacra Ijeing expressly stated not 

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

 out tile characters mentioned above as distinguishing Toxobrissus and Brissopsis — that we are 



' Hittner ((jber Parabrissus und einige aiulere alttertiiire Kchiniden-Gattungeii. Vcrliaiidl. d. K. K. geol. Reichs- 

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

 luiig von Taf. XIX. Fig. 8 durch Taf. XIX. Fig. 9 in Taf. XXI. Fig. 2 anzunehmen, diirfte sehr gewagt sein >. Also Poniel has 

 perhaps seen that; in any case he says {Classif. meth. p. 33): «le pretendu Brissopsis lyrifera de la Floride est probahlcnient 

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



