354 Mr. H. J. Carter 07i Points of Distinction 



concamerated form of the interior, rising evidently from the 

 central or primary cell of a pseudoconcamerated discoidal base, 

 closely resembling a discoidal foraminifer. The terminal 

 opening is also shown, as well as the sarcodal contents of the 

 concamerated cavity, consisting of granular sarcode charged 

 with ova ; and the peculiar form taken by the pseudopodia is 

 described in the branched variety {ojy. et loc. cit.) ; so that, 

 indeed, SquamuUna sco^yula prominently puts forth all the 

 points which distinguish a foraminifer from a sponge. 



My astonishment, therefore, may be easily conceived when 

 I saw the following footnote in Hiickel's ' Monographic der 

 Kalkscliwamme,' voL i. p. 456, translated in the 'Annals,' 

 by W. S. Dallas, F.L.S.. as " communicated by the author" 

 (vol. xi. p. 244, April 1873.) Hiickel there states : — 



" Whether the simplest sponge-forms, corresponding with 

 the picture of ArcMs'pongia^ still exist is not known. Possibly 

 a very near ally is the singular sponge which Bowerbank has 

 described as Haliphysema Tumanowiczii (Brit. Spong. vol. ii. 

 p. 76, fig. 359), and which Carter regards as a Polythalamian 

 {Squamulina) . I suspect, on the contrary, that it is a very 

 simple Myxospongia, which, like Dysidea, forms for itself a 

 skeleton of foreign bodies (spicules of other sponges, spines of 

 Echinoderms, &c.), but in other respects has the simple 

 structure of Oh/nthus.'''' 



But I am still more astonished at Hiickel's likening Squa- 

 mulina scopula to Dysidea^ since in Dysidea^ as well as in all 

 the sponges which draw in foreign objects to strengthen their 

 skeletons, these foreign bodies form the axis^ not the walls, of 

 horny fibre, or are cemented together by amorphous sarcode 

 into a fibrous structure, according to the nature of the species, 

 about which the soft portions of the sjjonge hang, as before 

 stated, like flesh on the bones of a human being — that is, out- 

 side the fibre. This is the case in Dysidea. On the other 

 hand, Squamidina scopxda builds up a similar structure, but 

 lives inside it — that is, inside the fibre as it were. 



Perhaps Polytrema ridtra, Dujardin (see Carpenter's ' Intro- 

 duction to the Study of the Foraminifera,' p. 235, Ray Soc. 

 Pub. 1862), most nearly approaches in structure to the sponges 

 which strengthen their skeletons with foreign material. Here 

 we have a cancellous structure whose cavities communicate 

 with each other, but finally terminate on the surface in little 

 circular areas, each of which is pierced, like a pej)per-box, with 

 a number of distinct holes, while the intervals are filled up by 

 the exterior termination of the clathrate skeleton, which, albeit 

 for the most part it consists of a thin curvilinear lamina of cal- 

 careous matter, frequently presents in its structure foreign 

 objects, such as the spicules of sponges, &c. 



