HYALASCUS. 87 



HYALASCUS TjrMA. 



Vase-like, firmly attached by contracted base; 

 large. Gastral surface lined with distinct endosomal 

 layer covering over the excnrrent canalar apertures. 

 Parenchymalia, diactins only. Hypodermalia, pentact- 

 ins supplemented with some diactins. Dermalia, gener- 

 ally rough pentactins; occasionally hexactins. Gas- 

 tralia, similar hexactins. Oxyhexaster represented by 

 hemiliexactinose and hexnctinose forms. Discohexaster 

 in one small form with very fine terminals. 



The genus was originally instituted by me for the reception 

 of a single species which I briefly described in 'g6 under the 

 name of TL sac/amlensis. F. E. Schulze ('97, p. 520), in Ins 

 revision of the Asconématidtç, placed this genus and species 

 under that familv. For the orounds that have led me to take 

 up the genus under the Rossellidiie, the reader is referred to my 

 Contribution HI. ('03, pp. 78-82). 



In '98 I referred to the same genus a second species, If. 

 glganteiis. And now T feel the necessity of establishing a third 

 and new s]iecies, H. similis. 



The genus seems most nearly related to ScypJiiiliuiii, Vifrol- 

 lula and Crater omoripha. Its distinction from tliese as well as 

 from certain other allied genera may l)e gleane<l from the dif- 

 ferential key given on p. 18. 



The three species, which are all of the genus at present 

 known, will in the sequel be described in detail. They may be 

 distinguished by the foUovring characters : 



