Dr. C. F. Liitken — On the OphiuridcB. 81 



true affinities; (3) the typical species, P. Milleri, Phill. (= P. 

 loricata, Williamson), rorerred by such distinguislied i)al!r!()nt()logists 

 as Forbes and Wright to Ojjhioderma. I li;ive vainly soiij^lit lor the 

 cause of this arrangement, which is directly contradicted by the 

 great radial plates, never to bo found in Ophiodcrma. The same 

 must be said of the other Liassic and Oolitic Ophiodermcc (0. E<jertoni, 

 0. tenuihranchiata, 0. Gaveyi, 0. carinata, and 0. Escheri). I sco 

 no reason at all why they should not be referred to Ophioijhjplia; thoy 

 must at least belong to a very closely allied genus ; perhaps I should 

 except 0. Egertoni, specimens of which, in the museum at Copen- 

 hagen, have the general aspect of Ophiodcrma. Ophi{y)coma granu- 

 losa, Eoemer, is quite indeterminable, but has nothing to do with. 

 Ophiocoma. 



Of D'Orbigny's genera, some are identical with living genera 

 {PalcBocoma = Ophioglypha, Ophiurella = Ophiocoma), some must 

 be rejected because their characters are based on the absence of some 

 part of the external skeleton, owing to the imperfect state of preser- 

 vation (as Ilylocoma, Ophiocoma'), while others may be retained 

 {Acrura, Aspidura), but without definite limits or satisfactorily es- 

 tablished characters. 



So much for the genera of D'Orbigny ! I shall briefly notice the 

 other species of fossil Ophiuridse, that I have found described or 

 enumerated by the authors. Ophiura Miirravii and WethereUi, Forb. 

 are justly referred to Ophioglypha ; and perhaps also Ophiolepis 

 Bamsayi, Wright, when it is more fully known. Ophiura granulosa 

 and svhcylindrica of Hagenow, and 0. olifex of Quenstedt are quite 

 indeterminable. 0. Bonnardi, Oppel, is, I believe, undescribed. 



Amphiura Pratti, Forbes, I formerly regarded as correctly 

 determined, judging from the original figure and description ; but 

 after having seen those of later date by Dr. Wright, I do not know 

 what to make of it. I cannot identify Ophiolepis gracilis, Allmann, 

 with any recent species : if completely known in all its details, it 

 would perhaps be the type of a peculiar genus. It is closely allied 

 to Amphiura, but the long arm-spines are an aberrant character : they 

 are, however, described as " rather short " by Mr. Walker. Ophiura 

 Gumdelii, Lindstrom, from the Jurassic strata of Spitzbergen, is 

 referred by its describer to Ophioglypha, and especially compared 

 with 0. affiais, but it has some remarkable characters of its own, e.g. 

 the deep fissures in the back of the disc between the radial scutes, 

 and the peculiar club-like form of the arms. 



From the formations older than the Trias, we only know some 

 Silurian species, described under the names of Protaster, Tceniaster, 

 Eugaster, and Ptilonaster. With the exception of a single very fine 

 specimen of Protaster Miltoni, I can only judge of these genera from 

 the descriptions and figures, but I am convinced that they are all 

 true typical Ophiuridce, having no affinities with the Euryalidce, nor 

 with the Asteridcs, as has been supposed. I do not believe that 

 Eugaster and Taeniaster are separable from Protaster ; the characters 

 given are either of a slight value, generally, for the distinction of 

 genera, or their real existence in nature appears rather doubtful. 



VOL. VII. NO. LXVIII. 6 



