Natural History of East Finmarh. 91 



how the process of modification takes jjlace and the various 

 forms are developed. As all the species cannot, in my 

 opinioD, remain in the two genera to which Hincks assigned 

 them^ I prefer to refer to them simply by their specific 

 names. 



The majority of the Cribrilinidse are furnished with pore- 

 chambers, but the following are without them : — melolontha, 

 no pore-chamber and only two rosette-plates on the whole 

 side ; nitido-punctata and figulina. Nitida has two pair of 

 large lateral pore-chambers and one distal, the last some- 

 times being divided into two. In annulata Levinsen has 

 figured (Zool. Dan. pi. v. fig. 24) the pore-chambers as very 

 irregular, one lateral pair and one or two distal, or two pair 

 lateral, the former of which meet in the middle of the distal 

 margin, and I have seen the same variations in British speci- 

 mens ; but in the var. spitsbergensis I have not seen any pore- 

 chambers in the example treated with liquor potassse, the side 

 walls are narrow and possibly the underlying pore-chambers 

 have been destroyed in the preparation : radiata and the form 

 mnoniinata have four pair of lateral pore-chambers and one 

 (or two) distal ; punctata has three pair lateral (and two 

 distal ?) : cryptocecium has three or four pair lateral and two 

 distal ; Bahaci has four pair lateral and Gattyce three pair 

 lateral. 



The cribriline portion of the front wall in Cribriliuidse is 

 built up by bars, which would seem to represent the spines 

 of the so-called '^Mcinbraniporidffi.^^ The diagrams annexed 

 indicate the process of development. The bar A always has 



its proximal end rounded, and this rounded end I shall call 

 the loop, C : in most cases the loop has its origin in the side 

 ivall, B, in the same maniler as a spine ; but in certain species, 

 as Gattyce, Balzaci, and jigulina, in which the areolated or 

 cribriliform portion only occupies the central part of the front 

 wall, and is separated from the side wall by a considerable 

 unsculptured interval, the " loops '^ have their origin in the 

 front wall and nut in the side. The bar is hollow^ and m 



