370 PROF. E. A. MIXCUIN ox THE BRITISiJ [DeC. 13, 



this respect ; but in the specimen (No. 4) ah^eady referred to as 

 having a tendency to diminution in the thickness of the large 

 monaxons, the slender forms are found varying from short ones 

 of 50 yLt in length to long hair-like forms exceeding half a milli- 

 metre in length (text-fig. 92, figg. 4fZ-4j, p. 367). The monaxons 

 showing this extraordinary development also tend to become 

 abnormal in form ; for whereas the ordinary examples of this 

 type of spicule are characterised by their pei-fect sti-aightness and 

 absence of any curvature, the elongated forms become irregularly 

 curved and wavy. I consider the special development of these 

 spicules in this specimen as an abnormality, due perhaps to some 

 special conditions of its habitat, of which unfortunately no record 

 is preserved. Another specimen in which the slender monaxons 

 are greatly elongated, but to nothing like the same extent, is seen 

 in Ko. 10 (text-fig. 92, figg. 5a-5g, p. 367). This specimen is 

 unique, in my experience, in another respect. While in all other 

 specimens I have seen the monaxons are distinguished by their 

 slenderness, whatever theii- length, from the other classes of 

 monaxons present, in this specimen these slender foi-ms show a 

 tendency to become thickened and at the same time evenly curved, 

 thus indicating a transition to the thicker types. 



(c) General Bemarks on tlie Species. 



This sponge, as has l^een said, ^vas first described by Montagu 

 in 1812 under the name Sjiongia complicata; but its distinctness 

 was not generally recognised until Haeckel in 1872 gave it pi-ecise 

 characters, thus determining definitely the species which must 

 henceforth bear the name complicata, whatever Montagu's specimen 

 may have been. 



Unfortunately, Haeckel overlooked the small monaxons in some 

 of his specimens, for Avhicli he I'etained the name comjMcata, but 

 saw them in a specimen for which he founded a new species, 2>ini(,s, 

 whicli must therefore i-ank as a synonym. There are, moreover, 

 other species in his monograph which must be put as synonyms 

 of complicata until further evidence be forthcoming as to their 

 distinctness. 



First and foremost among these is Ascortis fahricii, the Leueo- 

 solenia fabricii of Oscai- Schmidt. There is nothing whatever in 

 Schmidt's or in Haeckel's descriptions to differentiate this species 

 fi'om complicata. The diagnostic featui-e, absence of quadri- 

 radiates, is insufficient, since Haeckel records the frequent presence 

 of this type of spicule, and founds on it a '■ connexive Varietat " 

 which he names Ascandra fahricii. This proves that the diagnostic 

 absence of quadriradiates was in reality merely scarcity, a common 

 variation of this sponge. The small monaxons are not mentioned 

 by either writer, but Schmidt's bi-ief description testifies to his 

 having made a most cursory examination of the sponge, and 

 Haeckel overlooked them also in his complicata, so that this point 



