NO. 5 CLARK : ECHINI OF WARMER EASTERN PACIFIC 313 



lying flat and close so that the surface of the test is relatively smooth, quite 

 unlike the condition in the other species of the genus. Pedicellariae very 

 small and not abundant or peculiar. At each mouth angle is a group of 

 8-10 slender, acute primary spines, lying almost horizontally over the 

 mouth. Color old gold orally, more nearly deep colonial buff aborally. In 

 the largest specimens the color is very dull, especially on the upper side; 

 orally the yellow-brown shade is very evident. 



This very distinct species was taken by the Velero at 9 stations between 

 San Miguel Island, California, and the Coronados Islands, Mexico, in 

 4-30 fms. While most of the 118 specimens are young or very young, large 

 adults were taken at 5 stations. The young are commonly quite yellow but 

 the big adults are rather dull colored. A bare test when carefully cleaned 

 revealed well the extraordinarily small petaloid area. The very small size 

 of mouth and anus is another striking feature. 



Type. — Holotype, AHF no. 48, 82 paratypes. 



Type locality. — Station 976-39, north of Santa Barbara Island, Cali- 

 fornia, 15-20 fms, May 28, 1939. 



Distribution. — Channel Islands, California to Coronados Islands, 

 Mexico. 



Depth. — 4-30 fms. 



Specimens examined. — The type, paratypes and 35 specimens, from 9 

 stations. 



Dendraster mexicanus*, new species 



Plate 51, Figs. 37-39 



Length 60 mm, breadth 60 mm, height 9 mm. Lower surface nearly 

 flat, the mouth a little sunken. Test rather evenly elevated from margin to 

 apex which is about 28 mm from posterior margin. Madreporite just pos- 

 terior to apex. Petaloid area 32 by 33 mm with the anterior petal 18 mm 

 and each of the anterior laterals about the same. Tuberculation of test 

 very close and fine near margin but distinctly coarser on the elevated part 

 of test, particularly within the petals; on oral surface the tuberculation is 

 coarser and more widely spaced. Posterior petals about 15 mm long and 

 8 mm wide; they are slightly curved and diverge markedly, the inner 

 margins being 15 mm apart at tips; poriferous areas very wide (about 3 

 mm), the ridges between the pore-pairs are very narrow but carry a 

 crowded series of 3-9 minute tubercles. Areas between the poriferous 

 zones carry fairly numerous, but not crowded tubercles of diverse sizes; 



8 mexicanus, in reference to the southern habitat of the species. 



