152 , OPHIURANS. 



occurs in the West Indian region where Holothuria captiva, from which it can 

 scarcely be distinguished except by the anal teeth, is common. It occurs in 

 the Indopacific region with Holothuria difficilis from which again the anal teeth 

 are its one distinguishing character. On the other hand, it is utterly unlike 

 any other Actinopyga save for the presence of the anal teeth. Pearsons is 

 almost certainly right in removing it from Actinopyga but he throws no light 

 on the problem of its relation to the species of Holothuria mentioned. Pos- 

 sibly the presence of anal teeth is, in this case, not even a valid specific character 

 but it is hard to believe this is the case. At any rate, the occurrence of this 

 perplexing form, originally described from Florida, on the shores of Easter 

 Island is a matter of unusual interest. 



Summary of the Echinoderms collected by the Agassiz-Albatross Tropical Pacific 

 Expeditions of 1891, 1899-1900 and 1904-1905. 



As the present report is the last of those dealing with the Echinoderms 

 collected by Mr. Agassiz on his Tropical Pacific Expeditions, it is fitting that 

 the chief additions to our knowledge of the taxonomy of the Echinodermata 

 should be summarized. 



The Crinoids proved to be the least abundant of the five classes and only 

 nine species were taken. Of these two were unidentifiable but six of the 

 others were new. There is no record of the number of specimens. The most 

 notable of the crinoids are the two stalked forms Balhycrinus eqxiatorialis A. H. 

 Clark and Calamocrinus diomedae A. Agassiz. The latter, one of the most 

 notable stalked crinoids as yet taken, was made the subject of a detailed mono- 

 graph (Agassiz, 1892, Mem. M. C. Z. 17, no. 2). 



The Asteroids were fairly numerous but there were few species of ex- 

 traordinary interest. In all more than 1,300 specimens were brought home, 

 representing ninety species, of which sixty-nine were new. Of new genera, 

 five were established. The most notable forms are probably the two species 

 of the new genus Albatrossia, the numerous species of Hymenaster, and Zoro- 

 aster, and the Brisingidae. 



The Ophiurans were numerous both in specimens and species but unfor- 

 tunately there is no complete record of the number of specimens. There were 

 at least ninety-seven species taken, and of these sixty were new. One new 

 genus was described based on this material. The most noteworthy brittle-stars 

 are Gymnophiura mollis, Sigsbeia lineata, and Ophioderma pentacantha. 



