130 



PORIFERA. II. 



fully developed forms and from the few developmental forms, this spicule seems to be really diactinal. 

 b. Microsclera; these are only of one form, isochelae areuatae. The chelae are elegantly formed, the 

 shaft is evenly and rather highly curved, the terminal parts are comparatively small in proportion 

 to the length of the chela. The alae are drawn out to a pointed corner, and are somewhat tooth-like; 

 the tooth is narrowly lanceolate, pointed downwards, and there is a small, oblong tuberculum. The 

 shaft is not quite cylindrical, but a little compressed ; this compression may be more or less pronounced, 

 and the dorsal side of the shaft may thin to a more or less broad brim. In this respect there may 

 be great difference in different individuals. In some individuals the shaft is only little compressed, 

 and only very few chelae show a slight brim; in others chelae with brim and without brim are about 

 equally frequent, and in one specimen almost all the chelse have a brim, and only few are found 

 without brim. The more frequent the chelae with brim are, the broader is the brim. In the specimen 

 in which almost all the chelae are provided with a brim, this brim has frequently one or two incisions, 

 so that it is divided into two or three lobes. In by far most individuals the brim is narrow, and in 

 most of the chelae it is wanting, so that it seems as if its higher development is to be regarded as a 

 monstrosity. The length of the chelae is 0-034— 0-0429"™, and the thickness of the shaft is between 

 0-0014 and o-oo29 nim , according as it is seen from the front or from the side; in chelae with large brim 

 the breadth of the shaft may reach o-oo50 mm . A few developmental forms were seen; the fine ones 

 had a recurving at either end, but did not yet show any traces of alae. The chelae are found through- 

 out the sponge, and they are abundantly present everywhere in the dermal membrane, besides in 

 other places they are close-lying in the pore sieves in the strings of tissue between the pores. 



Locality: Station n, 64 34' Lat. N., 31 12' Long. W., depth 1300 fathoms, one specimen; station 

 18, 6i° 44' Lat. N., 30 29' Long. W., depth 1135 fathoms, three specimens; station 20, 58 20' Lat. N., 

 40 48' Long. W., depth 1695 fathoms, six specimens; station 36, 6i° 50' Lat. N., 56 21 Long. W., depth 

 1435 fathoms, ca. ten specimens. The stations are situated in the Denmark Strait, south of Greenland, 

 and in the southern part of the Davis Strait. The species is evidently a deep-water species, 1135 

 fathoms being the smallest depth, at which it has been taken. All the specimens are more or less, 

 some to a very high degree, filled with the light-gray mud of which the bottom at the mentioned 

 localities consisted; in it is found a great many Foraminifera and Coccoliths. This filling may, however, 

 at all events partly, have taken place in the trawl. 



Remarks : This species seems to be rather closely allied to the above mentioned D. abyssi Tops, 

 whose chelae, to judge from the figure, have a somewhat similar form, and whose dermal spicules are 

 tornota. Also this species is a native of considerable depths, between ca. 2000 and 2500 fathoms. Top- 

 sent mentions that it, like rhopalum, contained much bottom material. 



2. D. obesichela n. sp. 

 PL XIV, Fig. 2 a-d. 



Form? The dermal membrane thin, supported by bundles of dermal spicules. Spicula: Mega- 

 sclera: the skeletal spicules oxea 0-54 — 075""", the dermal spicules oxea o-j2 — o--/-/""*.- microsclera of two 

 forms, chela' arcuata: 0-026 — o'ojjy""". sigmata o m 02i — o'o6j""". 



