1887.] NATURAL SCIENCES OF PHILADELPHIA. 181 



as determined by other appendages of the gemmulse. Assuming 

 that the illustrations will sufficiently show the meaning of the spe- 

 <'ial terms used, the student is referred, without further preface to the 

 following "Key," by comparison with which he will without 

 hesitation be able to decide the (;e)ieric status of his specimen. 

 Fuller definitions Avill be given as each genus comes under no- 

 lice. 



KEY TO THE GENERA OF KKKSH WAiKR SPONGES. Carter's .System. 



1. GemmuljE surrounded by acerate (PI. VII c.c.c) or "cylindrical 



(PL VII b.b.b) spicules alone. (Plate V, figs, i, ii, 

 [[[ A Spongili.a. 



2. " surrounded by birotulate (PI, IX. %. iii. b.b.b etc.) 



spicules of a single class or type,^ resting by one 

 (the proximal) rotule upon the chitinous coat ; 

 diameters of the rotules equal or nearly so. (PI. 

 V, fig. iv, V and vi.) Mkyenia. 



3. " surrounded by birotulate spicules of two classes or 



types, both resting by one rotule upon the chitin- 

 ous coat ; the less numerous class longer than the 

 other. (PL VI, fig. i,) (PL XI. b.c. etc.) 



Hetekomeyenia. 



4. " surrounded by iniequibirotulatespicules(Pl. XII fig. 



i, ii, and iii. b.c.d. etc.) of which the proximal ro- 

 tule is much larger than the distal one. (PL VI. fig. 



[[^ TUBELLA. 



■5. " whose "crust" is charged with spicules from which 



the distal rotule has been entirely eliminated, leav- 

 ing the proximal rotule surmounted only by a 

 short, pointed portion of the shaft. (See Ann. and 

 Mag. 1881, PL 5, figs. 1 and 2.) Parmula. 



■*). " whose foraminal tubules are prolonged, their ter- 



minations broadly funnel-shaped or divided into 

 cirrous appendages of varying numbers and 

 lengths. (PL VI, figs, iii, iv, v and vi.) 



Carterius. 



1 Specimens are occasionally found with birotulates of a single type arranged 

 in two or three concentric series. For this form Mr. H. Mills proposed (Proc. 

 Am. Soc. of Microscopists, 1884) the new genus Pleiomeyenia; while Prof. 

 Vejdovsky has ?ne?-ged ivio species named on account of the same peculiarity into 

 'he common species E. miilleri. See "Diagnosis." 



