ASTHENOSOMA BYSTR1X. 29 



3.25 nun., the abactina] 5.50 i.. and the actinal 5 mm. j the height of the 



tesi was 9 mm.; with nine and ten plates in the interanibulacral areas. 



In a specimen measuring 5 mm. in diameter, the anal system measured 

 1.25 mm., the abactinal 3 mm., and the actinal 2 mm.; with seven and eight 

 plates in the interambulacral areas. 



Asthenosoma hystrix a. \ 



Asthenosoma Reyuoldsii A. A... Bull. 81. < '. /.., VIII., No. 2, p. 75, 1880. 

 .Mi.iiiMii.it. Santa Ci 103-373 fathoms. 



PI. MIL. PI. AVE. 



The differences which I noticed i Preliminary Report on the Blake Echini, 

 Bull. M. C X.. VIII., No. 2, i>. 75) in some of the larger specimens of Asthe- 

 nosoma collected by the Blake, seemed to be of sufficient importance to 

 separate them from A. hystrix under the name of A. Reynoldsii. A more 

 careful examination of the large series of Asthenosoma collected by the 

 Blake has satisfied me that the differences, striking as they appear at 

 first sight, are merely due t.> age, and that what I had called .1. Reynoldsii 

 in the Preliminary Report are only Luge specimens of .1. hystrix. Spe- 

 cimens measuring about 125 mm. in diameter are figured by Thomson in 

 the Porcupine Echini, Pis. EX1\ '.. LXV.; and l>\ me in PI. 11. of the Sassier 

 Echini (70 nun. in diameter). I have figured on Pis. Xlll. and XIV. two 

 specimens L65 mm. in diameter, showing the features characteristic of the 

 largest .1. Reynoldsii collected, which measured about L 70 mm. in diameter. 



In the smaller specimens, less than 70 mm. in diameter, the coronal plates 

 of both areas are relatively narrower than in larger specimens, and while 

 the general arrangement of the primary tubercles does not differ greatlj in 

 speciim ns of different sizes between 50 and 1 20 mm. in diameter, in the 

 ambulacral areas, or in the two areas above the ambitus, yet there are very 

 considerable differences to l>e noticed in the interanibulacral area- on the ac- 

 tinal side. We lind in larger specimens a third, and sometimes even a fourth, 

 vertical row of primary tubercles extending from near the actinostome to 

 above the ambitus. Compare PI. XIV. Fig. t, with the figures of Thomson 

 in the Porcupine Echini, and those of the Hassler Echini quoted above. 



The smaller specimens less than 70 mm. in diameter are usually of a 

 brillianl claret-color, but often of a light pink color with only darker 

 patch.- of d.ep claret on the actinal side; we find larger specimens 



