JOURNAL ^ZZT^ 



OF THE GAPncv> 



ROYAL IICROSCOPIGAL SOCIETY. 



AUGUST 1883. 



TEANSACTIONS OF THE SOCIETY. 



X. — On the Spicules of Cueumaria hijndmanni, C. calcigera, 

 and two allied forms. 



By Professor F. Jeffrey Bell, M.A., Sec. E.M.S. 



{Read 13th June, 1883.) 



Plate VIII. 



The descriptions given by earlier naturalists of the characters of 

 species of Holothurians lack the precision and exactness which has 

 been possible since the year 1844, when Diiben and Koren in their 

 classical essay laid a solid foundation for systematic discussions, by 

 giving an account of the characters of the microscopic spicules 

 which are found in the body-wall and the suckers of this group of 

 Echinodermata. 



No competent zoologist has since then failed to make use of the 

 weapon which the great Scandinavian naturahsts put into our 

 hands ; the only possible difficulty, indeed, that presents itself to 

 the mind is as to whether we are not here committing the same 

 kind of error as that which has been seen in many other depart- 

 ments where too much stress has been laid on a single character or 

 set of characters. 



As a matter of fact, however, we still require a very large 

 amount of definite information with regard to a number of forms, 

 and that even with regard to some of the best-known of the species 

 of the Northern Seas. Among those treated of by Diiben and 



EXPLANATION OF PLATE VIU. 



Fig, 1, la. Spicules from body-wall and suckers of Ciccumaria hyndmanni. 



„ 2, 2a. „ „ „ C. calcigera. 



„ 3, 3a. „ „ „ Cueumaria sp. 



„ 4, 4a. „ „ „ C. montagui. 



(All X 220.) 

 Ser. 2.— Vol. III. 2 I 



