DIAGNOSES OF THE SPECIES. 29-") 



malia, rough stauraetins and pentactins, tlio former pvo(l(^ininnt- 

 iiig. HoxHRtoTS, ossoutially as in 0. 7nßyeri. 



Goniis HYALASCUS T.r. 



(Diagiidsi^ nil p. S7). 



//. s'lf/fnufritsis T.r. — Bodv eoiiipnrativcly lirLii-wallcd, out- 

 bulged in the middle, with flaring oscular rim. lueurrent and 

 excurrent canalai- ajjertures under 2 mm. diameter. (lastral 

 cavity lined with continuous gastral layer. Discohexaster in one 

 S2:)herical form of 80-90/' diameter; each principal hearing usu- 

 ally 3 slender terndnals. 



//. similis Tj. — Quite like the foregoing species; hut the 

 discohexaster proper to that species is here exceedingly rare, 

 while the commonest discohexaster is a smaller and not spherical 

 form of 40-r)0 //. diameter in which 12 or more delicate terminals 

 to each ])rinci]ial form a se])arate, expanding and peiäanth- 

 like tuft. 



//. (fif/ffiifrns T.r. — Thick-walled ; with wide canals and 

 canalar apertures, giving a cavernous appearance to the wall. 

 The incurrent canals form an extensively intercommunicating 

 system. Clastral surface, as also the wall of the larger excurrent 

 canals, is lined l)y an irregularly meshed endosomal lattice, with 

 no continuous covering layer of gastralia over the meshes. T^isco- 

 hexaster in one spherical form of 30-38 /'- diameter, with 10 or 

 less termin-.ds to each principal. 



