18 PROF. E. A. MINCHIN ON THE [May 2, 



Clathrina spinosa Mincliin, ibid. 



Leucosolenia spinosa Breitfuss, 1898, Arch. f. Naturges. Ixiii. 1, 

 p. 213. 



(The following references, on the other hand, probably do not 

 relate to the true co7itorta.) 



Ascandra contorta Barrois, 1876, Ann. Sci. JSTat. (6) iii. Article 

 11, p. 35, probably refers to Leucosolenia compUcata. 



Leucosolenia contorta Carter, 1880, Midland Naturalist, ii. 

 p. 195. The author remarks that " Bowerbank's illustration of 

 the linear spicule is defective. There are tim forms, quite different 

 from each other and from Dr. Bowerbank's figure." I consider 

 it probable fi'om this statement that Carter was dealing with a 

 specimen of Leucosolenia complicata. 



Ascandra contorta Breitfuss, 1898, Arch. f. Naturges, Ixiii. 1, 

 p. 214, refers to a specimen of Leucosolenia complicata ; so pro- 

 bably also the sponge described and figured by the same author in 

 Mem. Ac. St. Petersbourg, 1898 (viii.) vi. p. 15, pi. i. fig. 1, and 

 cited by him in other memoirs. 



And finally it should be mentioned that the numerovis specimens 

 sent out from Sinel and Hornell's Zoological Station, Jersey, are 

 all, so far as I have seen, specimens of Leucosolenia co')nplicata. 



Diagnosis. — Triradiate systems equiangular, with or without 

 ijastral rays ; the quadriradiates generally more numerous than 

 the simple triradiates. Rays of the triradiate systems tapering 

 imperceptibly for the proximal half or two-thirds, then narrowing 

 moi'e rapidly to a sharp or moderately blunt point. Gastral rays 

 sometimes short, more usually longer than the basal rays, very 

 slender, sharp, and straight or irregulaily curved. 



Monaxons at least twice as thick as the basal I'ays of the tri- 

 radiate systems, — varying in diSerent specimens from a moderate 

 size to gigantic proportions, spindle-shaped, usually slightly curved, 

 and usually Avith a distinct constriction near the middle of their 

 length ; sometimes very few in number, sometimes absent 

 altogether. 



The chief objection that can be made, it seems to me, with 

 regard to my treatment of the species, relates to the position of 

 spinosa. Naturalists concerned chiefly with the arrangement 

 of specimens in bottles on shelves will perhaps object to my 

 " lumping" together two forms which can be separated by a definite 

 character, although by one only. Those who reason thvis will, no 

 doubt, prefer to retain spinosa as a "species" distinct from 

 contorta ; in that case the type of Bowerbank's contorta belongs 

 to the former species, a fact which raises alarming problems of 

 nomenclature. The range of variation seen in contorta has its 

 natural and logical termination in the form sp>inosa., and justifies, 

 in my opinion, placing the latter as a synonym. Moreover it is 

 often extremely difficult to be certain that monaxons are really 

 absent in a specimen of " spinosa." They may be so scarce that 

 they have been simply overlooked. 



After arriving at the above conclusions with regard to the 



