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Show 368 PROF. E. A. MINCHIX OX THE BRITISH [Dec. 13, colony, the unpaired rays vary from 70-90 /u, the paired rays from 65-80 p in length (text-fig. 93, figg. 6 «-6 h, p. 369). In the latter (text-fig. 93, figg. 8 «-8 j\ p. 369) the unpaired rays vary from 120-170 fx, the paired from 105-125 fu. With the increased size the rays also tend to increase in thickness, reaching 10 /x or slightly over in their thickest part. This is especially well seen in a specimen sent me by Topsent from Banyuls-sur-Mer, which is remarkable for the general thickness of its triradiates (text-fig. 93, figg. 9 a- 9 d, p. 369). It is interesting to note that it is in those two specimens with exceptionally large triradiates that I found barbed monaxons of the largest size, reaching a length of 425 /.i in No. 9 and 360 p in Topsent's specimen, while in No. 3 these spicules were below the average in length (150-200 /i); the small monaxons, on the other hand, did not show any noteworthy variation in those three specimens. Topsent's specimen possesses further interest as being the only example of this sponge which I have seen from the Mediterranean. The large barbed monaxons (b, 1) show great variations as regards curvature and length, but remain remarkably constant in their general appearance, as well as in thickness. Only in one specimen, No. 4 of my list, have I remarked a tendency to be below the normal in this respect (text-fig. 92, figg. 4 a- 4 c, p. 367). In length they may vary from 80 u to nearly half a millimetre, perhaps even more in some cases. The unbarbed large monaxons vary from straight to slightly curved, and may also vary in dimensions. But the greatest variations are shown by the slender monaxons (b, 3). In the first place, while, as a rule, they show no trace of a lance-head, in some cases they exhibit very distinctly a rudimentary barb at the distal end. This is the case in the specimen in Canon Norman's collection identified by Haeckel as complicata, No. 1 of my list (text-fig. 92, figg. 3 f - 3 i, p. 367). But the greatest variation is seen 111 length. In almost every specimen they vary greatly in Explanation of Text-fig. 93 (opposite). Spicules of Leucosolenia complicata. Figg. 6 « -6 /;. Spicules of one of the type specimens of Bowerbank's Leucosolenia contorta (British Museum, Bowerbank's Collection, No. 988, left-hand middle specimen), showing triradiate systems of unusually small size, a & b, triradiates ; c, a quadriradiate; d & e, slender monaxons showing distinct barbs ; f & g, large barbed monaxons; h, a large monaxon without barb.-Figg. 7 a -7j. Spicules of a specimen in the British Museum (Reg. No. 95.4.6.1) labelled " Leucosolenia botryoides " in Bowerbank's handwriting and " type sp." in Carter's handwriting. a & b, ordinary triradiates; c, a thickened triradiate; d, an ordinary quadriradiate ; e, a thickened quadriradiate ; f & g, slender monaxons; h, a large monaxon without barb ; i & j , large barbed monaxons.- Figg. 8 a -8 f Spicules of a specimen in the British Museum (Reg. No. 95.4.6.2) labelled " Leucosolenia botryoides " in Bowerbank's handwriting and " type sp." in Carter's handwriting, showing all the spicules above the average in size, a, a triradiate ; b, a quadriradiate ; c&d, slender monaxons; e&fi large barbed monaxons.-Figg. 9 a -9 d. Quadriradiate spicules of a specimen from Banyuls-sur-Mer, sent to me by Topsent, showing the unusually large size and thickness reached by some of the spicules (b and d). |