[DAWsoNl FOSSIL SPONGES AND OTHER ORGANIC REMAINS 105 



spiculog, short, and, in aome ca8o. expawded at theiv (,xt.-e,nitie8. Younir 

 m.l.vHhu, s seem to havo boon ^WobUar and probably sessile, while large 

 .ndnndualH had a ^lat base; but the ^cenera! form is greatly obscured by 

 crushing, especially in the larger specimens. 



Fta.lO.-Protospongiajjolynema. Primary, secondary 

 and tertiary spicules, x 5, " 



4.— Pkotospongia DELicATULA, Dawson. - 

 (Figs. 11 and 12.) 

 Globular or oblong in form, 1 to 4 cm. in diameter. Body spicules 

 cructorm, regu ar, forming a very dense mesh, abott 1 mm. or less in the 

 opening^ Osculum probably wide. Defensive spicules very short and 

 close. Several short anchoring-rods. Some indicatons of a double row 

 of spicules m the body-wall. The density of the spicular body-waH 

 causes It often to be encrusted and obscured by pyrites. 



t=P-- 



:}r 



m 



km 



Fig. n.—Protoapongia deUcatula. (a) Re- 

 stored, (b) Portion of base enlarged. 



Fig. 12. -Primary, secondary and 

 tertiary spicules, x 5. 



eottWW. 7"%'™Ph on fossil sponges, identifies this with Wal- 

 na sot w fh'' ^'-^ ( A^«n..m) subsph<,r.cus of the Utica shale, but com- 

 panson with specimens kindly furnished by Dr. Walcott shows Ihat there 



