MUSEUM OF COMPARATIVE ZOOLOGY. 177 



Loriol * to establish a new family Bourguetia^inida', which comprises the 

 two genera just mentioned, together with Batlii/ainux and Mesoo-iints, a 

 genus recently proposed by myself. De Loriol also inchides in it Ilycri- 

 nus of Danielssen and Koren ; but this genus is certainly identical with 

 Bathycrimu, which was founded by Sir Wy ville Thomson \ on an imma- 

 ture specimen dredged by the " Porcupine " in 2435 fathoms, two hun- 

 dred miles south of Cape Clear. His description J of tlie larger species^ 

 B. ahb-ichianiis, from the Southern Sea, seems not to have reached the 

 Norwegian naturalists before the publication of their genus liycrlnus, 

 which was founded on much more developed individuals than that 

 dredged by the " Porcupine." 



Of the four genera included in De Loriol's new family, Bourgueticrinus 

 and Rhizocrinus are the two most closely allied. The differences between 

 them are greater than was supposed by Sars, owing to his mistake about 

 the basals of the latter type, and may be summarized as follows : — 



Bourgueticrinus. Lower stem-joints not longer than wide ; while one or two at 

 the top of the stem are nnich longer than those below, and help to form the 

 " summit." Basals usually wider than high. 



Rhizocrinus. Lower stem-joints usually much elongated, two or three times as 

 long as wide. Those just below the calyx are the shortest, often being mere 

 disks. Basals usually much longer than wide, occupying the greater part of 

 the length of the calyx, which expands somewhat from below upwards. 



The last type to be mentioned is the remarkable genus Holojms, about 

 which much information will be found in a communication § by Sir 

 Wy ville Thomson to the Royal Society of Edinburgh, in 1877. Since the 

 publication of this paper Sir Wyville made a horizontal section of the 

 cup about two thirds of its height from the base. I was never fortunate 

 enough to learn his own views on the subject, but the appearance of the 

 section leads me to believe that the lower part of the cup is formed by 

 basal plates which project inwards and upwards above the level of the 

 outer edges of the radials, just as in Pentccc7^iuus.\\ 



* Paleont. FraiKj., loc. cif., p. 63. 



t The Depths of tlie Sea, pp. 450-454, fig. 73 ; and Proc. Roy. Soc. Edinb., Vol. 

 VII. pp. 772, 773. 



I " Notice of new Living Crinoids belonging to the Apiocrinida?," Journ. Linn. 

 Soc. Zoology, Vol. XIII. pp. 48-51. 



§ " On the Structure and Relations of the Genus Holojms," Proc. Roy. Soc. Edinb., 

 Vol. IX. p. 409. 



II Schliiter (loc. cit., p. 51) is inclined to believe that basals are present in Cya- 

 thidium spilcccense. Like Sir Wyville Thomson, I am unable to dlH'erentiate Cija- 

 thidium from Holopus. 



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