Whiteaves — Uintacrinus and Hemiaster. 289 



Hemiaster Vancouver 'ensis, sp. nov. 



Cast of the interior of the test widely suboval or subovate in 

 marginal outline, a little longer than wide, and widest at or a 

 little in advance of the midlength, with the posterior end 

 abruptly and almost vertically truncated in some specimens but 

 not so much so in others. Dorsal or abactinal surface depressed 

 convex, very slightly elevated, most prominent at a short dis- 

 tance from the posterior end; ventral or actinal surface flattened; 

 greatest height about one-half of the maximum length. Oral 

 aperture not well shown in any of the specimens collected, vent 

 small, a little higher than wide, placed high up on the truncated 

 posterior extremity and near the abactinal surface ; apical disc 

 situated at a considerable distance behind the midlength in some 

 specimens, but not very far from median in others. Ambulacra 

 very unequal in length ; the odd anterior ambulacrum being a 

 little longer than the anterolaterals, but rather indistinctly 

 defined at the anterior end, and the anterolaterals much longer 

 than the short posterolaterals. Anterior median sulcus shallow 

 but well marked, and giving a faintly emarginate or subemargi- 

 nate outline to the anterior end. Anterior ambulacrum entirely 

 included within the median sulcus; anterolateral ambulacra 

 petaloidal, narrowly elliptical and shallowly depressed ; postero- 

 lateral ambulacra also shallowly depressed, somewhat similar in 

 shape to the anterolaterals, but not more than one-half of their 

 length. Spines and exterior of the test unknown. 



The foregoing description is based almost exclusively upon 

 the two nearly perfect and undistorted casts from the Cow- 

 ichan River and Shopland, already referred to, and these may 

 therefore be regarded as the types of the species. 



Ottawa, August 23, 1904. 



