2 



int:' the knowlcdgu of the ueuus, that all new I'orms tall naturally 

 into one or other of these. To this rule the forms now under 

 consideration offer no exception, tliouuMi representin<; both groups; 

 aS'. sfiijjnalis and »S'. asptrfima, bclotiuing to the fluviatilis type, 

 i^.jiexispiiid and S. Oft<iiriit:nKis, to that of lacustris. 

 In the first series, are iticluded those spon<;illas in which the 

 licnimulo, or reproductive capsule, is built up ol'birotulate spicula, 

 placed side by side, and arranged with their axes radially. In 

 tlie second, the capsules are inore leathery, but covered, when 

 mature, with straight or curve<l spicula, arranged at right angles 

 to the radial lines. 



For details concerning tlu' cla>silication and morphology of tlie 

 SponglUldu:, reference should be made to Dr. Bowerbank's and 

 Mr. Carter's Memoirs. 



I append first Dr. Bowerbank's description of *V. Ihitcwni, as 

 given iu his monograph on the Spi>iiyillid(i .'■'•^ 



t^pongilla D-iir.soni, ]io\\cvhdnk. ••Sponge sessile?, branch- 

 ing; surface smooth, oscula and pores inconspicuous. Dermal 

 aud interstitial membranes abundantly spiculous; spicula fusi- 

 formi-acerate, entirely spined ; spines numerous, short, and 

 conical. Skeleton-spicula acerate or subfusiformi-acerate. Ovaria 

 spherical : dermal spicula numerous, disposed in flat fasciculi, or 

 groups of spicula parallel to each other ; groups irregularly dis- 

 persed ; spicula acerate or subcylindrical, entirely spined ; spines 

 numerous, obtuse, and ill-defined. Sarcode aspiculous. Colour, 

 in the dried state, emerald-green." 



JJ<ib., Kiver St. Jjawrence, Montreal ; a lake near Brockville. 



Dr. Bowerbank further adds, with reference ro this species: 



•' The dermal and interstitial membranes abound with teusion- 

 spicula, and especially the dermal one, in which they seeai to 

 attain their fullest degree of development. Their normal form 

 is fusiformi-acerate ; but, from the abundant production of the 

 spines at their terminations, they frequently appear to be cylin- 

 drical rather than acerate. They are disposed on these tissues 

 rather unevenly, abounding iu some spots, whiU they are euui- 

 paratively scarce iu others." 



" The spicula of the skeleton are of about the same propor- 

 tions as those of the European species. They are usually of the 

 regular acerate form, but occasionally become .rubfusiform." 



* i'roc. Zool. Sec. London, Nov. 1863, and Caiuulian Nuturulist, 18C4. 



