ECHINOIDEA. II. 97 



emphasized by Agassiz. It is mainly the large frontal tube-feet which are taken as a proof of this 

 affinity the striking resemblance of the young Brissopsis with its gigantic suckers in the odd 

 anterior ambulacrum (Rev. of Ech. PI. XIX. 12) to the full-grown Aerope, plainly shows the Brissoid 

 affinities of the genus* (Chall.-Ech. p. 190); but also the shape of the test is, if I understand it rightly, 

 taken as a proof of this affinity (Chall.-Ech. p. 196). Quite apart from the fact that it seems rather 

 exaggerated to term the frontal tube-feet of the young Brissopsis gigantic*, this isolated feature, the 

 large frontal tube-feet, does not appear to me a sufficient proof of near relation between these other- 

 wise very different types; the subanal fasciole so characteristic of Brissopsis seems especially a proof 

 against the suggested affinity with Aeropsis and Accste. Also the structure of the globiferous pedi- 

 cellariae is a proof against more close affinity of these forms, far more important than a possible 

 resemblance in the shape of the test of Aceste when seen in end view. 



If the view expressed above (p. 8485) of the primary classificatory importance of the structure 

 of the sternum be correct of which I for my part am fully convinced it naturally follows that the 

 affinities of Aeropsis and Accste. to Pourtalesia and other Ananchytid genera, likewise repeatedly emph- 

 asized by Professor Agassiz, are not real; they are merely superficial analogies. Aeropsis and Aceste 

 are rather primitive amphisternous forms, which cannot be more closely related to the higher meri- 

 dosternous genera, and neither can they be taken as showing the passage of the Pourtalesm-group 

 to the Brissina among the Spatangoids (Chall.-Ech. p. 190). 



26. Hemiaster expergitus Loven. 



PI. II. Figs. I, 4, 18, 20. PI. IV. Figs. 68, 1012. PI. XV. Figs. 9, 16 18, 24, 26, 3031, 35, 38, 44-45, 4748, 50. 



Synonyms: Hemiaster zonatus A. Ag. | 



gibbostis A. Ag. (? see below, p. 102 5). 

 Mentzi A. Ag. J 



Literature: Loven: Etudes sur les Echinoidees. p. 13. PI. V. 46 47. XI. 93 94. XIII. 114 20. 

 XXVI. -- On Pourtalesia. p. 53. PL X. 92. XVIII. 222. -- Bernard (78). Th. Mortensen: Some new 

 species of Echinoidea. p. 243. 



The specimens of Hemiaster dredged by the Ingolf, Michael Sars and Thor must un- 

 doubtedly be referred to the species described by Loven, //. expergitus. Professor Theel most kindly 

 sent me the type specimens of Loven so that I have been able to make a direct comparison, and 

 the identity is thus established beyond doubt The species was hitherto recorded, since Loven, only 

 from the Talisman by Bernard, and it is thus a fact of no small interest that it now proves to 

 occur also in the northern Atlantic, and evidently not very rarely. The specimens before me are of 

 different sizes, from 5" to 37 in length; I have further taken a quite young specimen of only 3 miD 

 length off Frederikssted, St. Cruz, ca. 500 fathoms, which evidently belongs to the same species. (Loven 

 had only a pair of young specimens of 10 14""" length). We are thus able to follow the changes 

 which appear with age. 



The shape of the test is seen from the figures representing the naked test and the test with 

 the spines (PI. II. Figs, i, 4, 18, 20. PI. IV. Figs. 6 8, 1012). The outline is oval, a little broader in the 

 anterior half. The abactinal side is almost flat, sloping rather strongly from behind towards the front, 



The Ingolf-Expedition. IV. a. 13 



