4 Mindeskrift for J. Steenstrup. X. 



Concrete". III. Les Echinodermes, 1903 (p. 146); by MacBride in "The Cambridge 

 Natural History" I. p. 494, 1906. Likewise B. Sturtz^) expresses the opinion that 

 Bell's observations ,,uber die Art der Ausbildung derjenigen Wirbelflåchen, die von 

 Wirbel zu Wirbel mit einander artikulieren, bezeichnen einen erheblichen Fortschritt 

 in der Erkenntnis der Ophiuren; selbst gegeniiber dem was schon Lyman daruber 

 bekannt machte" (p. 178). Further Koehler in his Monograph of the "Siboga"- 

 Ophiuroidea adopts the classification of Bell, and I have also myself, in my 

 first paper^), been of the opinion that Bell here "in der Hauptsache das Richtige 

 getroffen hat" (p. 517). H. Lym. Clark in his work on "the North Pacific Ophiurans 

 in the CoUection of the U. S. National Museum" 3) (p. 2) protests against the classi- 

 fication of Ophiuroids as it stands at present; but it does not appear, this protest 

 is meant to apply to more than the family-arrangement; at least he does not 

 mention the orders Zygophiuræ and Streptophiuræ. 



The primitive character of Ophioteresis is especially emphasized by Gregory 

 (Treatise on Zoology. III. p. 274 — 276). He states that in this genus, like Protasler 

 "there is a ventral groove", and "it has no ventral piates, but a small ambulacral 

 furrow, and thus agrees with the Palæozoic genera, for which Stiirtz in 1885 proposed 

 the family Ophioencrinasteriæ". Nevertheless he does not unite Ophioteresis with 

 those fossil forms, but suggests that "when the classification (of the living Strept- 

 ophiuræ) is attempted, probably Ophioteresis will form one family". MacBride 

 (Op. cit. p. 494) says that Ophioteresis "appears to possess an open ambulacral groove, 

 though this point has not been tested in sections". 



Against the assertion of Gregory that Ophioteresis has an open ambulacral 

 furrow, objection has been raised by W. P. Pycraft^) and E, A. Minchin^) in 

 reviewing the volume on the Echinoderms in the "Treatise on Zoology". I may 

 quote Minchin's remarks on this matter : ,,The genus Ophioteresis is used as an 

 argument for uniting the Asteroids and Ophiuroids on the ground that "the radial 

 ambulacral vessels and nerve trunks lie in shallow grooves on the ventral surface 

 of the arms" (p. 262; also pp. 270 and 274). The author gives no definite authority 

 for this statement, but leaves us to infer that he obtains the faet from Bell's 

 description of the genus. Bell, however, did not describe any such condition as 

 that which Gregory dwells upon so often and makes the basis for such important 



^) B. Sturtz. Ein weiterer Beitrag zur Kenntniss palæozoischer Asteroiden. Verh. d. natur- 

 hist. Vereins d. preuss. Rheinl. u. Westphalen. 66. 1899. 



*) Th. Mortensen. t)ber Ophiopus arcticus (Ljungman), eine Ophiure mit rudimentåren 

 Bursae. Zeitschr. f. wiss. Zool. Bd. 66. 1893. 



») Bulletin U. S. Nat. Museum, 76. 1911. 



*) Ann. Mag. Nat. Hist. 7. Ser. VI. 1900. p. 342. 



") Nature, Vol. 62, 1900, p. 646. 



