THE COAST OF CALIFORNIA. 33 



the animal is alive the plates are not visible, but when 

 (hied these structures are plainly brought out. This ge- 

 nus is one of the most highly colored of all the Asteroidea 

 in Californian waters, and the contrast between the colors of 

 the upper and lower surface is very marked.^ The very 

 })right red and orange specimens of Dermasterias are fe- 

 male, while the male is dark brown. The ova have a yel- 

 low color. 



In connection with the above description it may be of 

 interest to record the colors of Asierias^ exquisita. The 

 abactinal surface is brown, with white knobs or rounded 

 spines which are very conspicuous. Each knob is sur- 

 rounded by a circle of purple colored, filamentous, tentac- 

 ular bodies which are almost biacli. 



The starfish, Hymenasterminiatus, which is very common 

 at Santa Cruz, was often observed to be infested by a par- 

 asitic worm which from its intimate association is thought 

 to be parasitic upon the external surface of its body. 



Ophiothrix rudis Lyman. 



Balfour records that the gastrula cavity, archenteron, 

 of a species of Ophiothrix which he studied is formed by 

 invagination. Apostolides says that this structure in an- 

 other species is formed by delamination. 



The archenteron of Ophiothrix rudis is formed by in- 

 vagination. The following observations support this state- 

 ment. 



'The genus Dermasterias is so markedlj' different from otlier Asteroidea that a 

 new family is needed for its reception. I suggest the name Dermasteridaj with 

 the following characters. 



Arms five, covei-ed with a thi(;k, soft, leathery skin. No spines. Single row of 

 suckerless feet. Mouth as in Astropecten. Marginal plates smooth, prominent. 

 Dorsal plates of uniform size; no marked median dorsal. 



^The differences of this species from other known memiiers of the genus As- 

 terias are great enough to separate it and lo form a new genus for which the name 

 Calliasterias is suggested. 



