BY E. F. KALLMANN. 415 



or quite to the surface,' and in the outermost layer a few scat- 

 tered tylota only, mostly more or less vertically directed, are to be 

 seen. 



Spicules. — (rt)The principal megascleres are smooth styli and 

 strongyla, the former being about ten times as numerous as the 

 latter. The styli, which vary from (rarely less than) 140 to about 

 185 /i in length, and very seldom exceed 7 /x in diameter, are 

 straight or sliglitly curved (more especially near the basal end), 

 often very faintly dilated at the base, nearly cylindrical throughout 

 the greater part of their length, and, as a rule, gradually sharp- 

 pointed; the pointed end almost invariably exhibits irregularities 

 such as are commonly shown by spicules of the Axinellidae, and in 

 extremely rare cases is provided with a few minute spines, less 

 rarely an odd spine is to be observed on other portions of the 

 shaft. The slenderest forms are tylostyli, which are equal in length 

 to the fully-grown spicules. The strongyla range in length from 

 about 50 to upwards of 160 /x, and their maximum stoutness, 

 which is attained only by the shorter spicules, is 9-5/x; they not 

 infrequently show a deformity in the shape of a bulbous swelling. 

 Spicules of intermediate form between the longest strongyla and 

 the styli occur, but are rather rare. 



(5) Straight tylota, with nearly cylindrical shaft (often slightly 

 narrower at one end), and well-developed oval heads; measuring 

 from 155 to 195 jx long and at most 5*5 [x in stoutness. 



(c)Isochel8e arcuatae of ordinary shape; with well curved shaft, 

 slightly antero-posteriorly compressed; varying in length from 12 

 to 23 /x. Individuals of medium length are rare in proportion to 

 those of greater and of lesser length. 



(d) Sigmata; simple and contort; measuring between 1 9 and 

 36 /x in length from bend to bend, and up to 3// in stoutness. 



Embryos. — Deeply brownish-tinted embryos of oval shape, the 

 largest measuring 320 by 270 /x, were present, and most of them 

 contained spicules. The spicules were always of three kinds, viz., 

 straight or (very often) flexuous slender tylota, exceedingly slen- 

 der sigmata, and developmental chelae. Usually the tylota, like the 

 microscleres, were scattered; but in a few instances they were 



