6 BULLETTN "4, UNITED STATES NATIONAL MUSEUM. 



tubercles, two distinct secondary tubercles on each plate inside of, and not much 

 smaller than, the primary (in the description it is only said that "the median 

 granulation [is] finer, than in the other West India species of the genus,") the 

 interambulacra having a distinct naked median space, whereas the figure shows 

 no naked median space (in the description it is only stated that the interambu- 

 lacral plates "are covered by a comparatively coarse, irregularly arranged secondary 

 granulation.'') I had at that time no reason to doubt the correctness of the figure 

 given; the specimen examined in the British ]\Iuscum, however, could not pos- 

 sibly be identified with hartlMi as there represented and thus had to be made a new 

 species of the genus Tretocidaiis, to which genus it was referred on account of its 

 globiferous pedicellarife, which were essentially like those found in bartletti. 



During my visit to the U. S. National Museum I had occasion to examine the 

 specimens of Tretocidaris hartletti preserved in the collections of that institution 

 and I found that they had the same structure of the test as that described by me 

 in Tr. annulata, not as shown in figure 16, of Plate 2 of the BUTce Ecliini. Also a 

 specimen examined in the collections of the Peabody Museum, Yale University, 

 sliowed the same structure of the test. The result of these examinations was pub- 

 fished in Part 2 of the IngoJf Echinoidea, pages 169-170, namely, that my Treto- 

 cidaris annnkita was synonymous with Tr. hartletti, the quoted figure of the Blalce 

 Echini belonging to another species — or, in case this figure were correct, Tr. 

 annulata must be maintained, and then all the specimens of Tr. hartletti seen by 

 me in the U. S. National Museum and the Peabody Museum were not Tr. hartletti 

 but Tr. annulata. 



In Agassiz and Clark's memoir on the Cidaridas (Hawaiian and other Pacific 

 Echini) no mention is made of this ciuestion, but in H. L. Clark's important 

 paper The Cidaridfe, " page 203, it is pointed out tha-t my Tr. annulata can not be 

 distinguished from Tr. hartletti. Although no full description is given of the 

 species, it appears from his remarks thereon that he regards the specimens in the 

 U. S. National Museum as true hartletti, and as he has had access to the type- 

 specimen in the Museum of Comparative Zoology at Cambridge, this question has 

 been solved. Of figure 16, on Plate 2, of the Bhle Echini, which has caused the 

 trouble, no word is said. Possibty it was made from a specimen of Cidaris blakei 

 (A. Agassiz). Plate 14, fig. 7, represents part of an ambulacrum of this species. It 

 will readily be conceded that the similarity to the quoted figure from the Blal-e Echini 

 is considerable; only the latter figure represents the inner tuberculation a little more 

 regular than it is in C. hlakei. One more argument speaks for the correctness of 

 the suggestion that the figure represents really C. hhkei, namely, that no other 

 West Indian cidarid has the andmlacra thus tuberculated ; also the part of the 

 interambulacral area r('])resented in the figure agrees fairly well with C. hlaJcei, only 

 the tubercles around tlie areolcs are scarcely so prominent as in nature (see fig. 1, 

 on Plate 2 of the Blake Echini, which gives a good representation of this struc- 

 ture in 0. hl/tlcei). 



In the Hawaiian and other Pacific Echini, the Cidaridae, it is pointed out that 

 the globiferous pedicellarife of Tr. hartletti may show a verj^ considerable variation, 



o Published in December, 1907; the setond part of the IngoJJ Echinoidea was published in 

 November, 1907. 



