NORTH AMERICAN STARFISHES. 11 



Q 



tended for the support of the abactinal floor, either in this genus or in 

 Crossaster. In Sohister it forms a broad band when it connects with the 

 abactinal surface, and is gradually changed into a mere chord at the point 

 of attachment to the interbrachial basal plates. These partitions are 

 all exactly similar to the one supporting the stone canal. At the base 

 of the arms the sides of adjoining arms come together, forming rounded 

 angles, and do not, in the specimen examined, form an interbrachial par- 

 tition for the support of the abactinal floor (see PI. XVII. Fir/. 3). The 

 reticulation of the sides of the arms and of the abactinal region is com- 

 pact, composed of small meshes forming diagonal lines across the arms, 

 and more or less irregularly radiating lines from the centre of the disk. 

 All the plates of the actinal floor carry tufts of small spines (PI. XVII. 

 Fig. 2), arranged usually in parallel rows, corresponding to the long axis 

 of the plates; so that on the actinal side the spines of the interambu- 

 lacral plates are at right angles to the arms; on the plates forming the 

 triangular interbrachial space, the spines diverge from the actinostome, 

 while those of the plates at the angles of the arms, of the arms themselves, 

 and of the abactinal surface, form more or less circular tufts arranged 

 on the lines of the plates of these surfaces. 



Solaster endeca and Cribrella sanguinolenta are both found on the two 

 sides of the Atlantic, occurring in Norway, Denmark, Great Britain, the north- 

 west coast of France, Iceland, Greenland, Labrador, and as far south as Massa- 

 chusetts Bay ; C. sanguinolenta extending as far south as Long Island Sound. 



CribreUa sanguinolenta. 



Cribrella sanguinolenta Lutk. 1857. Vidensk. Meddol. 

 Asterias sanguinolenta O. F. Mull. 1776, Zool. Dan. Protl. 



Fl XVIII. 



The genus Cribrella is most closely allied to Solaster. It has, like So- 

 laster proper, a compact system of limestone network, forming, when de- 

 nuded of spines, small meshes on the abactinal surfoce (PI. XVIIL Fig. 1), 

 while the actinal surface and a part of the edge of the arms are covered 

 with larger plates, forming longitudinal rows parallel to the longer axis 

 of the arms, with more or less irregular shorter rows at right angles to 

 the axis (PI. XVIIL Fig. 4). The arrangement of the spines on this net- 

 work is very similar in the two genera, consisting of short sharp spines 

 placed on the abactinal surflice, citiier in clusters or in semicircular fan- 



