350 Bibliographical Notices. 



three are continental. The two former both belong to the genua 

 Rhizocrinus, of which no exclusively abyssal species are known, 

 though it has been met with at sixteen out of the thirty-four sta- 

 tions in the abyssal zone." Of Pentacrinus four species have been 

 found in the abyssal zone, whilst two of these are also continental. 

 Baihycrinus, on the other hand, has never been found at a less depth 

 than 1600 fathoms, and embraces four out of the eight species peculiar 

 to the abyssal zone. " No fossil Baihycrinus is known, however, 

 and the genus has no special affinities except with Rhizocrinus, of 

 which it may almost be said to be the ' benthal ' representative. 

 Of the four remaining abyssal species one is the sole representative 

 of the remarkable genus Hyocrinus, and has only been met with at 

 1600 fathoms and still greater depths. Like the Comatulid genus 

 Thaumatocrinus, which occurs at 1800 fathoms in the Southern 

 Ocean, it has certain strong points of resemblance to the Palaeocri- 

 noids." The other exclusively abyssal forms are two species of 

 Pentacrinus and one of Metacrinus. One species of Metacrinus occurs 

 both in the abyssal and continental zones. " Pentacrinus ranges back 

 to the Trias and Rhizocrinus to the Eocene or Upper Cretaceous. But 

 they are both abundant at depths of less than 100 fathoms, Penta- 

 crinus occurring in the Pacific and in the East-Indian Archipelago, 

 as well as in the Atlantic and among the Caribbean Islands ; whilst 

 Rhizocrinus, though limited to the eastern hemisphere, ranges 

 through over 100 3 of latitude." In conclusion, after reviewing the 

 distribution of the recent Neocrinoids both in time and space, the 

 author remarks : — " In spite therefore of the existence of a few cha- 

 racteristic abyssal types, it is somewhat of an exaggeration to speak 

 of the Stalked Crinoids as a group ' on the verge of extinction,' of 

 which a few survivors may occasionally be discovered in the deeper 

 parts of the great ocean basins." 



In an Appendix are discussed a number of topics raised by 

 several works which have appeared during the passage of the Report 

 through the press. Among the more important of these may be 

 noticed the following. The first " Note " deals with the question 

 of the apical system in Echinoderms generally. Prof. Loven's views 

 on the homologies of certain plates of the Crinoidal calyx in other 

 Echinoderms have been previously discussed by the author and others. 

 As, however, the opposing arguments have not been refuted in the 

 recent work of the veteran Swedish naturalist on Pourtalesia, and 

 as these opinions have been followed by other writers without any 

 additional arguments in their favour, the question is again passed 

 in review, and most cogent reasons are again adduced and strength- 

 ened, at least in our opinion, beyond refutation, by recent discove- 

 ries in the embryology of Asterids and Ophiurids, for rejecting the 

 homologies which Prof. Loven seeks to establish between the dorso- 

 central of an Echinoid or Asterid and the under-basals of a dicyclic 

 Crinoid. In connexion with this subject reference is made to cer- 

 tain conjectures of Prof. Perrier's, which an echinodermatist may 

 well describe as eminently sensational ! That writer considers (1) 

 that the embryonic "basals" of an Asterid, which primitively sur- 



