ECHINOIDKA. II. 129 



lenger-specimen from Bermudas — in the Albatross s specimens the short form of tridentate pedi- 

 eellarire differs a little from that of the , Challenger -specimen, the outer, widened part of the blade 

 being a little shorter and sharper set off from the narrow lower part (PI. XVI. Fig. 14); quite short 

 specimens of this form, corresponding to that figured in PI. XVI. Fig. 3, I have not seen in any of 

 these specimens; neither were ophicephalous pedicellariae found in any of them. This difference in 

 the pedicellarise is certainly too unreliable for regarding the * Challenger -specimen as specifically dis- 

 tinct from the Albatross~>-specimens. Nevertheless I am not quite sure, whether or not more than one 

 species of Alacropneustcs is found in the American waters. So considerable differences are found among 

 the specimens in the outline of the test, in the development of the petals, in the number and size of 

 the primary tubercles of the abactinal side, that it might well deserve a close investigation, if all 

 these different looking specimens are really one and the same species. I may mention here that in a 

 specimen from < Albatross» St. 1109 in the Museum of Yale College, there is no trace of the peripetalous 

 fasciole; the specimen otherwise agrees with Alacropncustes, and in any case it is no Spatangus pur- 

 pureas, as might otherwise be inferred from the wanting of the fasciole. 



The genera Spatangus and Macropncustes are evidently- very closely related. In the structure 

 of the test, pedicellarise and tubefeet they agree almost completely; in fact, the only essential differ- 

 ence is the presence of the peripetalous fasciole in Alacropneustcs. 



29. Spatangus Raschi Loven. 



PI. I. Figs. 4—5. PI. II. Fig. 19. PI. XVI. Figs. 17, 23, 28. 



Literature: Norman: Shetland Dredging Report II. Rep. British Assoc. 1868. p. 315. («Spa- 

 tangus meridionalis •). — Loven: En ny Art af Slsegtet Spatangus fran Nordsjon. Ofvers. Vet. Akad. 

 Forhandl. 1869. p. 733. Tail. XVIII. — Agassiz: Revision of Echini, p. 159, 567. PL XXV. Fig. 35. 

 XXVI. Fig. 23. — Wyville Thomson: «Porcupine»-Echinoidea. p. 750. — Grieg: Overs, nordlige 

 Norges Echinodermer. p. 33. — Bell: Echinodermata off the S.W. Coast of Ireland (69). 1889. p. 442. 

 — Catalogue Brit. Echinoderms. p. 167. PI. XVI. Fig. n. — Hoyle: Revised list of British Echinoidea. 

 p. 426. — Doderlein: Arktische Seeigel. Fauna Arctica. IV. p. 3S3. Echinoiden d. deutschen Tiefsee- 

 Exped. p. 262. Taf. XXXIII. Fig. 4. XLVIII. Fig. 2. 



Xon.: Agassiz: < Challenger -Echinoidea. p. 171. — Bell: Echinoderma of South Africa. I. 

 Echinoidea. p. 173. 



This species is, like the preceding one, very well described, so that only a few remarks have 

 to be added. — Like Sp. purpurcus it may have the two sides of the test unequally developed, though 

 not so much as in that species, judging from the specimens before me. — Photographic figures are 

 here given of a large, beautiful specimen, quite typical, except in the curious fact that the two pores 

 included by the subanal fasciole are present only on one side. — The subanal fasciole is evidently 

 apt to disappear in this species. Of 8 specimens examined by me the fasciole is completely developed 

 only in two; in three of them it is more or less rudimentary, and in three of them it has quite 

 disappeared. 



The pedicellarise have been figured by Agassiz in Rev. of Ech. (the short tridentate form) 

 and by Doderlein (Echinoidea d. deutsch. Tiefsee-Exp. PI. XLVIII. 2, the slender form of tridentate 



The Ingoll'-Expedition. IV. 2. 1 7 



