FASCICLES OF STAEFISHES. 121 



which the edge of the arm is divided by the deep furrows, allowing 

 the passage of the water; at their crossing, the furrows form larger. 

 more prominent openings ; the edges of all these rectan- j,jg ^q 



gular spines are crowded with fascioles. The genus Cri- 1!**^ jc^j^swtj ,t|b' 

 brella is interestino- as showing the gradual transition of VjjJl'l^tp' 



the interambulacral and marginal papillae into tufts of **^f%f^^''y 



such minute spines that the difference between them ' 



and true fascioles is hardly appreciable. In fact, in So- 



laster we have already certain parts of the surface covered by such 



minute spines that we must consider them as rudi- 



^_^ mentary fascioles and as probably acting as such. 



4\ jAK'*' ^ Fig. 17, a cross section of Cribrella, shows a close 



fe,Cr^L-^'-CJ. <;^ approximation to the cross section of Luidia as far as 



'^0^fW'^'i the tufts of spines are concerned ; these need to be 



'"A but slightly more crowded to form a 



. . . . ^ie- 18. 



most effective sieve. Seen in profile in a section {Fig. 18), ^ 



the tufts of spines, the interambulacral papillae, are seen ^"^.^'^-^^ 



to be somewhat more crowded into tufts than is the case 

 in such genera as Asteracanthion. A similar arrangement 

 is also found in Solaster (see Fig. 8), where the spines of the interam- 

 bulacral plates, with the exception of those of the so-called jaws, are 

 arranged in closely crowded tufts. 



NOTE. 



The arrangement of the Starfishes into families from the study of their 

 hard parts does not differ materially from the families adopted by Perrier 

 in his Revision of the group.* He himself has in a general way made 

 use of the characters furnished by the skeleton to limit the families he 

 has recognized. The modifications we should suggest go so far as to 

 transfer Pycnopodia from the Asteriadi^ proper, and Crossaster from the 

 Echinasteridge, placing them in close proximity to Brisinga, while Solaster 

 (limited) and Cribrella would be placed with the Asterinidae. 



The disposition of the digestive cavity and its appendages does not 

 appear to furnish systematic characters of great value. The anatomy of 

 the ovaries of the coecal appendages of the digestive cavity proper with 



* Asteriadse, Echinasteridae, Liackiadse, Goniasterid^, Asterinidae, Astropectinidae, Pterasteridae, 

 Brisinaidae. 



