224 Proceedings of the Royal Physical Society. 



In lateral aspect the hydrothecse are characterised by their uniform 

 width, the bottom of the cup being if anything rather wider than the 

 aperture. On the margin there is no constant arrangement of " two small 

 denticles, on each side in towards the hydrocladium," such as Miss Bonnevie 

 describes, nor are there always " long portions of it smooth." 



In my specimen the whole of the margin is crenulated, but the scallops, 

 varying in intensity, are more strongly developed towards the hydrocladium, 

 and fade away towards the anterior. The anterior portion of the margin 

 is projected into a double tooth, the larger portion of which forms a 

 long, frequently incurved point, which is supplemented by a smaller tooth, 



Fig. 3. 

 Portion of hydroclade, with hydrothecre, of Gladocarpus bonneviecc. 

 s. s„ supracalycine sarcotheca. t., anterior tooth. 



x 50. 



i. sept., internodal septum. 

 n., node. 



h., hydro theca. 



m. s., mesial sarcotheca. 



i-th. r., intrathecal ridge. 



lying on the inner surface near the base. There is a well-developed 

 intrathecal ridge projecting from the adcauline wall across half of the 

 hydrotheca cavity. In all but the youngest hydrothecae a small septum 

 runs across the cavity of the mesial sarcotheca. 



The upper portion of a supracalycine sarcotheca is tilted backwards 

 towards the hydroclade. It is not cylindrical but scoop-shaped, the side 

 towards the internode being open, and the margin is crenulate. A well- 

 marked thickening of chitin indicates the division between the free and 

 adnate portions. Three sarcothecye, not two as Miss 'Bonnevie states, 

 accompany the base of eacli hydroclade : two lie on the anterior of the 

 basal process, one distal, the other proximal ; while the third sarcotheca 



