MUSEUM OF COMPARATIVE ZOOLOGY. 193 



Agassizia excentrica A. Ag. 



Station No. 20, Lat. 23° 02.5' N., Long. 83° 11' W. 220 fms. 

 Station No. 36, Lat. 23° 13' N., Long. 89° 10' W. 86 fms. 

 Station No. 21, Lat. 23° 02' N., Long. 83° 13' W. 287 fms. 

 (Sigsbee.) Off Havana. Lat. 22° 09' N., Long. 82° 11' W. 242 fms. 



Meoma ventricosa Lutk. 



Station No. 10, Lat. 24° 44' N., Long. 83° 26' W. 37 fms. 

 Station No. 36, Lat. 23° 13' N., Long. 89° 10' W. 84 fms. 

 (Sigsbee.) Off Havana. 127 fms. 



Schizaster (Periaster) limicola A. Ao. spec. nov. 



Plate III. 



Station No. 49, Lat. 28° 51|-' N., Long. 89° 01 1' W. 118 fms. 



This species belongs to the generic group of Schvuister, separated as Periaster 

 by D'Orbigny from the genuine Schizaster. Test quite globular, in outline 

 from above angular, posterior extremity vertically truncated, slight keel be- 

 tween posterior petals near apex ; anterior extremity truncated vertically from 

 the edge of the peripetalous fasciole, with a shallow ambulacral groove. The 

 lateral anterior petals are nearly twice as long as the posterior one, as well as 

 broader. The petals are all about equally sunken. The peripetalous fasciole 

 is in shape and position that of Schizaster proper, but there is no lateral fasciole 

 extending under the anus, as in Schizaster proper ; the anal fasciole is narrow, 

 extending only a short distance on the sides of the test. 



The test is thickly covered with primary tubercles of a uniform size, carrying 

 short, slightly curved spines on the sides of test. The tubercles are more 

 crowded within the fasciole and on the abactinal region of the odd posterior 

 interambulacral area. The coronal plates between the fasciole and the anal 

 system are quite bare, with few tubercles on the outer edges. On the actinal 

 side the primary tubercles are larger, more distant, except on the actinal plas- 

 tron, where they are closely crowded and carry longer, larger, and curved pri- 

 mary spines. The actinal lip is very sharp and prominent, one large row of 

 exterior plates round the anterior edge of the actinostome, smaller, irregular 

 plates within. Anal system quite small for such a large species. The separa- 

 tion of this group of Schizaster as a generic type seems very doubtful. It is 

 based solely upon the more globular outline of the test and the discontinuity 

 of the latero-anal fasciole. It may be convenient to form a subgeneric grouj) 

 with these characters ; but when we get to such forms as Sch. ventricosus and 

 Sch. japonicus, it certainly becomes very difficult, if not impossible, to draw the 

 line of demarcation. We have something of the repetition of the numerous 

 generic subdivisions attempted by Troschel in the genus Trijmjlus and its allied 

 forms leading to Faorina and the like, while this is a deviation in the direction 

 of such genera as Periaster, Epiaster, Hemiaster, and the like. The structure of 

 the odd anterior ambulacrum of this species has all the characteristics of Schi- 



