HYALASCUS SAGAMIENSIS. 89 



firmly attached to the 8ul)stratuin bv the contracted lower end. 

 In short, the shape of the species seems to be essentially the 

 same as that which I shall later descri])e for H. similis (text- 

 fig. 3, p. 96). 



As it was, the specimen (PI. VII., fig. 1) was vase-like, 

 bulging oat on one side at the middle of the upper half, in 

 which part the greatest breadth measured 230 mm. Entire 

 length 500 mm. Shape of cross-section somewhat angular on one 

 side but otherwise rounded. From the broadest part the body 

 narrowed gradually towards the torn off liase ; superiorly it also 

 showed a slight and gentle contraction before the irregular out- 

 flaring of the oscular region. The osculum, surrounded by a thin, 

 undulating and apparently simple-edged rim, measured 160 mm. 

 across in one direction and 140 mm. in another. Compared with 

 the size of the specimen, the wall must be said to be rather thin. 

 In the broadest part of the l)ody the thickness measured only 

 about 10 mm. and in the lowest part, where the gastral cavity 

 had been opened by the tearing off of the base, about 12 mm. 



Both external and internal surfaces are tolerably smooth. 

 The apertures of the canals, incurrent as well as excurrent, are 

 small, all being under 2 mm. in diameter. This doubtless stands 

 in a measure in relation to the fact that the sponge-wall is 

 dense and moderately firm. 



The dermal layer of the ectosome is so fine as to be scarcely 

 percejDtible with the naked eye. Under the lens its minute 

 meshes appear to be generally quadrate in shape. The hypo- 

 derraal latticework, just discernible by the unaided eye, comprises 

 irregularly angular meshes not more than 1 mm. in length of 

 sides. Aside from the genuine hypodermal beams there are dis- 

 tinctly observable on the outside a number of much coarser, 



