PORIFERA. II. 



53 



mentioned, a coating layer of the same nature as in the preceding species is found on the stalk below 

 the part carrying branches. It is most frequently very thin, and at the lowermost part of the stalk 

 it is at most o-2 m '" thick. It consists of close-packed, finely spinulous tylostyli, and is otherwise of the 

 same structure as in the preceding species; it becomes also snowy-white when dried. In the stalk the 

 spicules are united by a clear mass of spongin. 



Spicula: a. Megasclera. The megascleres of the skeleton are partly styli forming the axis, and partly 

 subtylostyli forming the skeleton of the branches and also occurring in the axis. The styli are straight 

 or slightly curved; they have a short, most frequently somewhat stubby point. They are fusiform, 

 also tapering somewhat towards the rounded end, and here they end with a somewhat more abrupt 

 tapering. Also in this species they may be divided into two groups; the longer, slenderer, oftenest 

 straight ones, and the shorter, thicker, and curved ones, but they pass into each other without any 

 marked boundary. The length varies from 0-63 — roi m,n , and the thickness from 0-020— 0-0357"""; the 

 longer ones did not commonly reach a thickness of o'C^o"" 11 . As in the preceding species the shorter 

 and thicker styli become more predominant towards the base of the stalk. The subtylostyli are 

 straight; they are fusiform and taper somewhat towards each end, the point is short, but rather sharp. 

 The head is placed a little below the rounded end and is most frequently a rather slight swelling. 

 The length of the subtylostyli is rather constant and is between o'58 mm and o-ji" 1 " 1 . The thickness is 

 o-on— o-oi8 mm , most frequently about o-oi7 mm . The spicules of the coating of the stalk are finely spinu- 

 lous tylostyli ; the head is marked in different degrees, most frequently rather distinctly, sometimes it is 

 placed a little down on the needle; the opposite end is long pointed, but the outmost point is stubbv 

 or cut off. The tylostyli are irregularly curved and sinuous. The length is between o-oo. mm and o-iq mm > 

 the thickness about O'ooi — 0-003™'". b. Microsclera are anisochelse palmatse of two forms and sigmata. 



1. The characteristic anisochelse are those typical for the subgenus, and they are of quite the 

 same form as those in pennatula. Their length is o-oio— o-on""", and their breadth is ca. 0'005' nm . 



2. The large anisochelse are also af a similar form as in the preceding species; the shaft is 

 straight; the larger end is not subject to the variations in form and size found in pennatula, but 

 makes always about half the length of the chela; the alse are folded far round on the side, and their 

 lower edge is rather straight without forming a far drawn out lower corner. The tooth is about as 

 long as the alse and is somewhat narrower than these; at the end it is cut off with rounded corners; 

 a long, downward pointed tuberculum is found. With regard to the smaller end of the chela the 

 description given under pennatula will almost entirely hold good; the only difference being that this 

 end in proportion to the size of the chela is smaller than is most frequently the case in pennatula; 

 also it is generally less irregular, and the variation consists chiefly in the fact that the middle tooth 

 is either whole or split. The length is 0-051— oo6i mm , the breadth 0-020 — o-o25 ,nm , and the thickness of 

 the shaft is about o-oo5 mm . 3. Sigmata; these are of the same form as in pennatula with only little 

 curved shaft and short ends, bent in a hook-like way. The shaft is likewise compressed or sharpened 

 like an edge inward towards the bendings, and they are contort, most frequently a quarter of a turning. 

 The length is 0-018— o-02i mm , the thickness in the middle is ca. o-ooi mm . The microscleres occur in 

 large numbers in the dermal membrane and in the tissue of the part carrying the branches. 



As will have been seen, this species is very closely allied to the preceding one, and differs 



