56 



PORIFERA. II. 





the lateral branches consists of short subtvlostyli. The skeleton of the coating layer of the stalk 

 consists of closely interwoven, finely spinulous tylostrongyla. The spicules of the axis are united by 

 a clear mass of spongin. 



Spicula : a. Megasclcra; these are the styli of the axis and the subtvlostyli of the lateral 

 branches, besides the spicules of the coating layer of the stalk. The styli in the axis have in this 

 species no abrupt tapering towards the head-end, and as the subtylostvli show most frequently an 

 almost indiscernible swelling, the difference between them is chiefly to be sought in the size. The 

 styli, to be sure, vary somewhat in form and size, but they cannot here be said to be divided into two 

 groups. They are straight, or slightly, only rarely a little more highly, curved; they are slightly fusi- 

 form with the greatest thickness in the middle. The point may be a little varying, but is always short 

 or rather short; most frequently it is bounded by straight lines. The length is 0-39 — o-65 mm , the 

 extreme measures, however, occurring rarely. The thickness, which has no definite proportion to the 

 length, is between o-oio mm and o-024 mra . The subtvlostyli are straight, only sometimes quite slightly 

 curved. They are only a trifle thicker in the middle than towards the ends; the head, which is placed 

 a little down on the needle, is generally a scarcely perceivable swelling; the point is short, but bounded 

 by straight lines. The length is 0-268— 0-36""", the thickness is 0-007 — o-on mm . The spicules of the 

 coating of the stalk are minutely spinulous tylostrongyla; the}- are more or less irregularly curved, 

 most frequently to a rather slight degree. The head is round and distinetlv developed, they do 

 not taper much towards the opposite end, and this end has a little swelling, so that in form they 

 approach tylotes. They are smaller than in the preceding species, the length is o-o68— o-095 mm , and 

 the thickness about o-ooi mm , a little more or less. b. Microsclera are anisochelse palmatse of two sizes 

 and sigmata. 1. The characteristic small anisochelse are of the type of the subgenus, and 

 are of the same form as in the preceding species; they are, most of them, ooio mm long and o-oo5 mm 

 broad, but chelse may be found reaching to a length of o-oi4 mm . 2. The large anisochelse 

 are also of a similar form as in the two preceding species. The shaft is straight; the larger end is 

 about half so long as the whole chelse; the tooth is considerably narrower than the alee, it is broadest 

 below, and rather straight cut off with rounded corners or sometimes more rounded; a long, down- 

 ward pointed tuberculum is found. The smaller end is more regular than in the preceding species, 

 and its form is more like that of the common type. The shaft has a pair of short alas, rather broad 

 above, and forming together a triangle; then there is a curved tooth of similar size, most frequently, 

 however, a little shorter than the alse. As the tooth is in a rather oblique position to the shaft, it 

 appears always somewhat shortened, when the chela is seen exactly from the front, and its curved form 

 is also seen. Accordingly, when the tooth has this form, the structure of the smaller end is quite 

 normal; the tooth, however, is often split into two lobes, and the splitting may be more or less pro- 

 nounced; lateral lobes, however, are never found. Also here the tooth is so thin and transparent, that 

 a clear view of the form can only be got by regarding the chela from the end. The length is 

 0-044 — o-054 mm , the breadth about 0'02i ram , and the thickness of the shaft is about o-oo4 mm . 3. Sigmata 

 are of the same form as in the preceding species with the same edge-like expansion of the shaft 

 towards the ends, and they are also contort. The length is 0-015 — o-oi7 mm , and the thickness about 

 Q-OQjmm aj] forms of microsclera occur in great numbers in the tissue. 



