

PORIFERA. II. 



189 



styli are evenly curved, sometimes straight, with shorter points than the oxea; they are 0-408— o - 49 ,m " 

 long and ca. 0-014 — o - oi6 mm thick, and are thus thicker than the oxea. To judge from the preparation 

 there is no reason to doubt that both forms belong to the species. The dermal spicule has been 

 figured incorrectly by Carter; it is a tylote, most frequently quite straight, about equally thick through 

 its whole length, with a distinct swelling at either end. Its length is 0-298 — o - 357 mm , and the thickness 

 is ca. 0-007""". The length of the ancorse is o - 055 — o - o6 ,nm and the length of birotulce 0-015 — o-oi8 mm . 

 On the other hand, I am not able to see from the preparation, how many teeth the ancoras and 

 birotulae have; but it may be decided that Carter's statement of the ancora having six teeth is not 

 correct; perhaps it may have six, but most frequently it has more, and, as usual, the number is not 

 constant. Birotulae, according to what I have been able to count when they were seen from the side 

 have most frequently twelve to fourteen teeth. Both ancorae and birotulae are very similar to the same 

 bodies in oxcata. The bows mentioned by Carter, which were only found in one of his specimens, 

 are quite surely foreign bodies, neither are they found in the preparation I have examined. 



This species is closely allied to oxcata, and it shows also conformity to varidens, but it is 

 separated from both these species by the occurrence of both styli and oxea. 



Locality: 6i° 10' Lat. N., 2'" 21' Long. W., depth 345 fathoms (bottom temperature -h i°i C.) (The 

 Porcupines-Expedition). 



4. I. dubia n. sp. 

 PI. XVIII, Fig. 4 a-f. 



Incmsting. The dermal membrane supported by recumbent bundles of dermal spicules. The 

 skeleton consisting of irregularly situated single spicules, spicnla-bundlcs, and here and there fibre-like 

 parts. Spicula: Megasclera: the skeletal spicules styli 0-46—0-536""", the dermal spicules tylota 0-34 — 

 0-36'"""; microsclera of two forms, isancorce ungu/fcrce with seven to nine free teeth 0-038 — 0-050""", biro- 

 tulm zuith eleven to fourteen teeth 0-018 — 0-021""". 



Of this species we have only one specimen, a quite small incrustation, placed on a dead bala- 

 noid shell. The greatest extent of the incrustation is i4 mm , the thickness does not exceed i ,nm . The 

 colour (in spirit) is somewhat dark brown. The surface seems to be smooth. Oscula and pores were 

 not seen. 



The skeleton. The dermal skeleton. In the dermal membrane recumbent bundles of dermal 

 spicules are seen, supporting the membrane and forming the dermal skeleton. The main skeleton: 

 As far as I have been able to examine from the slight material, the main skeleton consists of quite 

 irregularly lying spicules, mostly single, and here and there bundles, which may form fibre-like parts, 

 but meshes are not formed. A slight amount of spongin is found where the spicules are united. 



Spicula: a. Megasclera. 1. The skeletal spicules are styli; they are slightly curved, and 

 the curve is most frequently found nearest to the head-end; sometimes it is more even through its 

 whole length, or a little irregular. They are evenly and middle long or rather long pointed. They 

 show the peculiarity that they have almost always some slight spines or rather are slightly uneven at the 

 upper end; this feature is exceedingly slight, often almost imperceptible, but only rarely quite wanting. 



