Lutken — On Pentacrinites and Sea-Lilies. 17 



undoubtedly a true Pentacrinus, and . the former only as a slightly 

 deviating sub-genus. The magnificent Pentacrinas of Jura, (P. briar cus 

 and P. subangulai-is) difi'er in a higher degree as in the more branch- 

 ing arms, in the small radiaria, and in the solid plates of the perisoma. 



As to the true confines of the family of the Pentacrines, the author 

 thinks them very uncertain, and he also considers the question of the 

 arrangement of all sea-lilies in natural groups, still to be in a highly 

 unsettled state. Some have aranged them in articulated and tesselated, 

 (Crinoidea AU.TICULATA and tesselata). Those naturalists who 

 acknowledge the Ckinoidea akticulata as an indej)endent order, 

 number all species, younger than the palaeozoic formations, excepting 

 Molopiis and Marsupites, amongst them. They consider all the Cri- 

 NOiDEA TESSELATA as Palceozoic. But Dr. Liitken thinks this opinion 

 untenable, and it seems to him impossible to draw definite lines 

 between them. " If you take to the definition," he says, " that those 

 Sea-lilies are articulated, which have the radialia of the pelvic cup 

 free, that is, articulated between themselves, not united by seams, 



it may be answered that the Jurassic Apiocrinus has 



the radialia united by small intercalated interradialia, and the radialia 

 are thus immoveable, and not free." Moreover, the Paleozoic 

 Taxocrinus has the radialia quite as free as the Pentacrines, and ought 

 therefore to be ranged amongst the Crinoidea articulata. A 

 satisfactory systematical arrangement of the Crinoidea is, nevertheless, 

 highly desirable, as their forms almost daily increase in number. 

 The author is very right in dwelling on the undue eagerness with 

 which some palaeontologists, who, with a very slight knowledge of 

 the living crinoids, create so-called new species, often founded on few 

 and insufficient fragments. Although Dr. Lutken does not yet consider 

 it time to establish a true system of the Crinoidea, he gives what he 

 calls " a guiding thread " through this maze of forms. He then in 

 the first place designates as subordines, (a) the Cystidea, and (b) the 

 JBlastoidea, in opposition to (c) the true Crinoidea, and amongst the 

 last, he separates as families, (1) the genus Holopus with Cyathidium, 

 (2) Cupressocrimis, and (3) Antliocrinus, [Crotalocriniis) , both distin- 

 guished by the peculiar structure of their arms, (although so widely 

 unlike each other,) and by the absence of " pinnulte " ; perhaps also, 

 (4) Ctenocrinus, (5) Eucalyptocrinus, so different from all true Crinoids 

 in its whole structure. Then there rests the chief mass, (6) of all 

 typical Sea-lilies, and as central or typical genera amongst these may 

 be discerned, I. — Pentacrinus, (with Aledo, Miller icrinus, Taxocrinus, 

 aniJEncrinus); II. — Apiocrinus, (with Guettardicrinus); III. — Platy- 

 crinus and Actinocrinus. 



The remarks of Dr. Lutken on the sexual organs of the extinct Cri- 

 noidea are very important. It is undecided whether the living Penta- 

 crinites have a mode of reproduction resembling that of Alecto, with 

 the ova and the spermatic fluid enclosed in the pinnulce of the arms. 

 The specimens of the European Museums have been searched in vain, 

 the pinnulee are in no way so inflated as in Alecto. On the other hand, 

 there is no fact that contradicts the almost generally spread opinion, 

 that the sexual products in all typical Sea-lilies have been lodged iu 



TOL. IV. NO. XXXI. 2 



