102 The Ottawa Naturalist. [August 



truncated abruptly and obliquely by the facet for the arms, angle 

 of facet with general side of cup being 135. The facet is shallow- 

 ly excavated with contour almost circular, but broader than high, 

 width 4 mm.; height 3.1 mm.; axial canal small, ovate, marginal, 

 its acutely pointed apex opening directly into the ventral groove, 

 which forms an obtusely angular notch in the centre of the upper 

 margin of the plate. Right and left posterior RR a little smaller 

 than the rest. Superior anal plate x pentagonal, equal in size to 

 the r. post. R. and facetted above for the reception of plates of 

 the anal tube (vide intra). Cup-plates thick ; all rounded towards 

 the sutures, especially in the upper part of the cup ; outer surface 

 apparently smooth, but where the test is well preserved, as on 

 post B. and ant. R, are slight traces of shagreen ornament 

 Measurements in millimetres : 



Width Width Length of suture 

 Height, below, above. between plates. 



IBB 4- 2.5 5. 3. 



l - ant - B 8. 5.4 7. 4.5 



ant. R 6.5 7. 6.4 4. 



to bottom of facet. ... 4. 



r - P st - R 5- 5-4 4-75 4- 



to bottom of facet .... 2.75 



a "*l* 4-8 4-7 3-75 { J.'. ^ ^ 6 



Each of the sutures bounding RA is 3 mm. long, and the 

 plate in each direction is 3.6 mm. 

 Relations of the species : 



The radials slope outwards towards the facet, in the way 

 characteristic of Botryocrinus. The axial canal is quite distinct 

 from the ventral groove, though not actually separated therefrom 

 by stereom. The sides of the ventral groove slope inwards at a 

 wide angle, and at the same time separate from one another, so 

 that the communication between ventral groove and axial canal 

 becomes wider. Right posterior radial has portions of 3 or 4 

 rather solid covering plates. The chief point of difference between 

 Homocrinus and Botryocrinus, so far as the dorsal cup is con- 

 cerned, lies in the number of plates supported by the anal plate x. 

 These plates are not preserved, but one can see the facets for 



