762 MR. A. G. THACKER OX [June 16, 



Leucosolenia canariensis (Miklucho-Maclay). (Plate XL. 

 fig. 3 & text-figs. 157-160.) 



Synonymy : — 



Nardoa canariensis Miklucho-Mac-lay. 



Narcloa sulphurea Miklucho-Maclay. 



N'ardoa rahra Miklucho-Maclay. 



Tarroma canariense Haeckel (Prodromus). 



Tarroma suljjhicretc^n Haeckel (Prodromus). 



Tarroma ruhrum Haeckel (Prodi'omus). 



Ascaltis canariensis Haeckel [141. 



Ascaltis compacta Schuffner [22]. 



Ascaltis canariensis Lakschewitsch [16]. 



Ascetta coriacea, n.var. Ascaltis coriacea Fristedt [13]. 



Leucosolenia nanseni Breitfuss [4]. 



Ascetta coriacea Arnesen [1]. 



Leucosolenia tenitijnlosa Dendy [12]. 



The examination of a number of Ascons in this collection has 

 convinced me that I have to deal with a sponge that has been 

 previously described under several different names and from 

 various widely separated localities. The sponge in question is to 

 be regarded as a close ally of Leucosolenia coriacea, one of the 

 commonest of Homoccela, but it diifers from the latter species in 

 one essential character ; some of the spicules develop a fourth 

 ray, thus becoming quadriradiates. 



In 1872, in his great monograph ' Die Kalkschwamme,' Haeckel 

 described a sponge from the Canary Islands which was charac- 

 terised by having small, completely regular triradiate and quadri- 

 radiate spicules with bluntly pointed rays ; this sponge he called 

 Ascaltis canariensis. The form had been previously described 

 both by himself and by Miklucho-Maclay under three specific 

 names, a misconception which arose owing to the supposed specific 

 value of the difierent colours exhibited by different specimens of 

 the species. This Ascon was similar to L. coriacea, but differed 

 from the latter by the presence of quadriradiates and by the 

 smaller size of its spicules. 



Some thirteen years later Lakschewitsch [16] recorded the same 

 species under the same name from Minorca, 



In 1898, in describing a collection of Calcarea from Spitzbergen 

 (a preliminary account of which he had issued two years pre- 

 viously [3]), Breitfuss [4] described a sponge which he considered 

 new to science and which he named Leucosolenia nanseni. 

 Having regard to the results of the present investigation, I think 

 this form cannot be regarded as specifically distinct from 

 Haeckel's Ascaltis canariensis, and indeed Breitfuss himself 

 noticed the great similarity between the two forms, for at the 

 end of his description of L. nanseni he says : — " Das Skelet von 

 Leucosolenia nanseni erinnert etwas an Leucosolenia {Ascaltis) 

 canariensis (M.-Mcl.), unterscheidet sich aber von dieser durch 

 die Grosse der Nadeln, welche bei letzterer Species beinahe dreimal 



