SILICIOUS AND HORNY SPONGES WILSON. 427 



the larger ones, is distinguishable. Stephens, 1912 (pp. 32-33), 

 would also continue to distinguish M. macilenta from M. aegagropila, 

 referring to the former species sponges in which the anisochelas 

 fall in two groups, to the latter those in which the anisochelas are 

 all of one type and scattered singly, not in rosettes. Vosmaer and 

 Pekelharing have, however, laid stress on the variability of the 

 anisochela in their species. 



MYCALE EUPLECTELLIOIDES (Row), var. REGULARIS, new variety. 



Esperella euplectelUoides Row, 1911 (communicated, 1910), p. 333. 



Station D5136, a colonial mass consisting of three tubes united 

 laterally and below, outer surface of the tubes bearing numerous 

 lobular projections which give evidence of a tendency to become tubu- 

 lar. Largest tube 200 mm. high, diameter of terminal aperture and 

 middle of body 80 mm., smaller below ; this is about the size of the 

 type. Wall of tube thin, in general about 1 mm. thick, thicker in 

 the immediate region of a spine. (See below.) 



Station D5145, a colonial mass including three tubes similar to 

 the above; these are fused, in places, laterally and basally. Height 

 of tubes 150 mm., diameter of aperture and middle body in one, 60 

 mm., in the others, about 40 mm. 



Dermal membrane of outer surface of a tube scarcely porous to 

 the eye, but in reality perforated by the abundantly scattered 

 small pores. Lining membrane of inner surface studded with very 

 numerous small oscula, 1 mm. and less in diameter. The thin wall 

 of the tube in some specimens is interrupted by a few rounded gaps, 

 of varying size, several millimeters in diameter; these have smooth 

 edges and are doubtless healed wounds. Sponge flesh whitish, 

 skeletal fibers brown or yellow. 



The reticulum of spiculo-fibers which supports the wall is very 

 similar to that of the type, but instead of being irregular is regular 

 in that longitudinal main fibers and connectives are distinguishable. 

 Main fibers ascend, more or less parallel to one another, toward the 

 rim of the vase; they are 3-5 mm. apart. Connectives simple or 

 reticular, often 2-4 mm. apart. The entire reticulum is very coarse, 

 sizes of meshes about as in type. 



Outer surface of variety covered with sharp strong spines, com- 

 monly about 3 mm. long, which project more or less upward. 

 The spines are oblique branches of the main fibers and have the same 

 structure as the latter. In the type the outer surface is covered with 

 the bare, branching, tree-like ends of the larger fibers. In both 

 variety and type the inner surface of the sponge is comparatively 

 smooth. 



