Verrill, Notes on Madiata. 589 



gated, mdeniug but little outwardly and somewhat acuminate at the 

 end, whicii is often nearly enclosed by the pore.s. The interambula- 

 cra are broader and decrease much more rapidly toward the apex 

 than in C rosaeeus. Anal opening transversely oval, or rounded, sit- 

 uated about its own diameter from the edge of the shell. 



Length of largest specimens 4*G0 inches; breadth :5-90; height 

 1*15. Length of anterior petal, from the apex, TOO; its breadth 82; 

 breadth of enclosed space '50; length of anterior petals 1"70; breadth 

 •85; breadth of enclosed space '48; length of posterior petals r80 

 and 1"85 ; breadth '94 ; of enclosed space "58 and '60 ; diameter of anal 

 area *20 ; of actinal opening '3 3. 



Thirty-five specimens of this species are contained in the collection. 

 They show but little variation in outline, except what is due to age, 

 though some specimens are more elevated toward the apex than others ; 

 in regard to the flatness or concavity of the lower side there is, how- 

 ever, great variation, though Dr. Gray used this character in dividing 

 the genus into sections. The youngest specimens are 2*30 long by 

 2-10 wide, and are more oval in form and scarcely angular, but have 

 the flatness and form of ambulacral rosette characteristic of the larger 

 specimens, as well as the same position of the anal opening. 



From C. rosaceus of the Atlantic this species differs widely, the 

 former having a much more elevated and thick form, with broader 

 and more obovate ambulacra, which are much more swollen ; the 

 lower side is much more concave, and the anal opening nearer the 

 edge. 



La Paz, — J. Pedersen. 



Dr. Gray erroneously gave Borneo as the locality of his specimen, 

 which ]\Ir. Agassiz has identified, by direct comparison in the British 

 Museum, with specimens sent by me. 



BrisSUS Obesus Verrill, (pp. 316, 315). 



These Transactions, p. 316. 1867; Proc. Bost. Soc. Nat. Hist., xii, p. 382, 1869. 



A larger specimen, with part of its spines, collected by Capt. Ped- 

 ersen at La Paz, agrees well in form and other characters with the 

 original specimens. The spines are silvery white and slender, on the 

 upper side decreasing regularly in length from the peripetalous fasci- 

 cle to the margin; the upper ones being -10 or -12 long, the lower 

 ones -25 to "28. Those near the margin beneath are quite long, -35 to 

 •38, those near the mouth being largest. This specimen is 2-65 inches 

 long; 2 broad; 1-40 high. 



