BY E. F. HALLMANN. . 541 



original description, tlie size of the spicules is given as 70 by 

 2-6000ths of an inch — i.e., 296 x 8"4/t, but this, I think, must 

 be due either to an error of measurement or to a misprint;. 



(ii.) Tlie variously curved, usually more or less flexuous mega- 

 scleres are mostly strongyla, but individuals with sharp-pointed 

 ends are also numerous. They range from about 200 to 580/x in 

 length and from 1 "5 to 7/x in diameter. The acutely-ended 

 spicules, as a rule, are more or less abruptly-pointed, i.e., are 

 tornota; but more or less oxea-like forms are not rare. Some of 

 the shortest among the latter spicules are hai-dly to be distin- 

 guished from the oxea that derive from the stylote megascleies. 



Microscleres. — {i.)The sigmata are invariably more or less 

 contcu't, though seldom to such a degree as to appear 3-shaped 

 when seen from the side; they are 15 to 20/x in length measured 

 from bend to bend, and about 1/x in stoutness. 



(ii.) The trichites are of two sizes as regards length, the shorter 

 measuring from 15 to 28/x, the longer from 37 to about 60/x. As 

 already mentioned, the former occur onl\' in dragmata, the latter 

 both in dragmata and scattered singly. 



Cehatopsis Thiele. 



Definition.— XyiiixeW'idm of erect, lamellar or ramose habit; 

 t3'pically with an axially condensed skeleton deficient in spongin. 

 Megascleres either of two distinct kinds — styli (sometimes in 

 part secondarily diactinal) and elongated flexuous strongyla, — 

 or the latter spicules are absent. Microscleres: smooth microxea 

 only, typically occuri'ing most abundantly in the dermal layer. 



Type, C expansa Thiele. 



The genus was instituted by Thiele(38) for four species from 

 Japan, differing from all previously known Axinellidaj by the 

 presence of microscleres of a single kind in the form of smooth 

 microxea, and further characterised according to the generic 

 diagnosis —(i.) by the presence of smooth stylote megascleres 

 "die ein festes Axenskelett bilden, von dem nach Peripherie 

 radiare Style ausgehen", (ii.) by the very small amount of spongin 

 present, and (iii.) by the almost complete restriction of the 

 microscleres to the ectosome, where they constitute a dermal 



