222 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Plethotaenia, 1 gen. nov. 



Type, Macropneustes spatangoides A. Agassiz, 1883. Blake Ech., p. 64. 



The Blake collected near St. Cruz and near Barbados, at depths of 82-273 

 fms. fragments of dead, bare tests of a spatangoid which Mr. Agassiz at first 

 referred to Spatangus purpureas. In the Challenger Report he lists the same 

 species from near Bermuda, but later he decided that the Blake specimens 

 at any rate were not Spatangus and he accordingly described and figured them 

 as a new species which he referred to the fossil genus Macropneustes. As 

 Duncan (1889. Journ. Linn. Soc. Zool., 23, p. 254) has pointed out Macro- 

 pneustes is an ill-defined and unsatisfactory group, but whatever may be decided 

 as to its fate, it does not seem possible to properly include in it the Blake species. 

 Nor do I see how this species, so far as the unsatisfactory material at hand 

 permits me to judge, can be referred to any other known genus and I have 

 therefore given it a new generic name. Mortensen (1907. Ingolf Ech. pt. 2, 

 p. 128) refers the Challenger specimen from Bermuda and various specimens 

 from the Albatross collections, which he has seen, to the Blake species but 

 as he says that one of the specimens has no trace of a peripetalous fasciole. 

 the whole matter needs further investigation. 



Linopneustes. 



A. Agassiz, 1881. Challenger Ech., p. 167. 

 Type, Palaeopneusles murrayi A. Agassiz, 1879. Proc. Amer. Acad., 14, p. 210. 



The limits and relationships of this genus are by no means satisfactorily 

 determined. That it is nearly allied to Palaeopneustes is indicated by the 

 general character of the test and to some extent by the pedicellariae but the 

 presence of a subanal fasciole in Linopneustes seems a fact of too great impor- 

 tance to be outweighed by these resemblances. There can be little doubt that 

 Elipneustes and Eupatagus are near allies and for the present the genus may 

 stand near them. Koehler considers de Meijere's Palacopncushs speetabilis 

 a Linopneustes but in this I am unable to follow him because of the absence 

 of the subanal fasciole in that species. It seems very doubtful whether murrayi 

 and e.recnlricus are really distinct species and I am equally in doubt whether 



1 IIXtj&k = a great number -f raivla = ribbon, band, in allusion to the number of bands in the 

 peripetalous fasciole. 



