I2 o PORIFERA. II. 



thickness is ca. 0-017 — o - 025 m,n . Besides a great many much finer, very long pointed forms are found, 

 which pass evenly into the thicker ones, and are, no doubt, developmental forms. The smaller oxea 

 are of a quite similar form as the large ones, they are evenly, rather slightly curved, and have also 

 evenly tapering points of middle length. Their length varies from 0-268 — 0-35™™, and the thickness 

 from 0-013 — o-oi8 min . A few intermediate sizes between the two groups may be found. Fine develop- 

 mental forms are also found of the small oxea. 1 ) b. Microsclera; these are of only one form, isochelse 

 arena tse; they are of a quite characteristic form, the shaft is highly bent, but the curve ma)- otherwise 

 be somewhat varying; the tooth forms such an angle with the shaft, that a straight line drawn from 

 one end of the shaft to the other will pass through or along the teeth. The tooth is narrowly ellip- 

 tical, and there is a longish tuberculum broadest downward; the alse are of the same length as the 

 tooth or reach a little farther down, and when the chela is viewed from the side, they end in a round 

 lobe. Sometimes the chela is so highly bent, that the teeth and alse of the two ends meet, and the 

 bend may be so strong, that the teeth and alse overlap each other. This fact leads then to some 

 irregularity, the teeth are bent each to its own side, and they get a more or less wry form; on the 

 other hand I have seen no coalescing, neither between alse nor teeth; a coalescing may often appear 

 to have taken place, but by a sufficiently exact examination it is seen that the parts only pass over 

 each other, but are not coalesced. Together with the strong bend an alteration of the dimensions of 

 the single parts of the chela takes place; both alse and tooth become longer, and from the tuberculum 

 a continuation reaches farther down the tooth. This irregularity of the chelse may in some individuals 

 be of frequent occurrence, so that by far most of the chelae are irregular, while in other individuals it 

 is far more scarce. The length, which is a little dependent on the curve, varies between 0-030 and 

 o-04 mm , and the thickness of the shaft is 0-0033— o-O04 mm . Developmental forms of the chelae are rather 

 frequently found, the youngest forms are fine and have rather short recurved ends; at this stage they 

 may to some degree remind of sigmata; by and by tooth and alae are developed. The chelae are found 

 throughout the tissue, but are specially numerous and very close-lying in the dermal membrane. 



Embryos. In one of the specimens embryos were found abundantly. They are scattered in the 

 tissue, and each of them is surrounded by a thin membrane. They are about globular, and have an 

 average diameter of about o - 47 mm . The examined ones showed no spicules. 



As I have had one of Armauer Hansen's type specimens, I have been able to identify the 

 species with certainty; otherwise the determination would have been impossible. The D. clavellata 

 established by Arnesen I.e. I have, likewise by examination of a type specimen, been able with cer- 

 tainty to identify as flabdliformis. Arnesen evidently has only had young specimens; to be sure she 

 states the size to be 25 cm , but the specimen sent to me is only 25""", and the figure of the stalk on 

 Taf. IV, Fig. 4 shows that it is at most a few millimetres thick, so that there can scarcely be any 

 doubt that 25 cm is a misprint for 25""". 



Locality: The Ingolf, station 7, southeast of Iceland, 63"" 13' Lat. N., 15 41' Long. W., depth 600 

 fathoms, two large specimens; station 85, southwest of Iceland, 63° 21' Lat. N., 25° 21' Long. W., depth 



■) In the mentioned smallest specimen the spicules were a little smaller, the skeletal spicules measuring at most 

 0-4 i mm , and the length of the dermal spicules keeping near the lower limit. The microsclera, on the other hand, were of 

 full size. 



