196 



PORIFERA. II. 



dermal spicules are tvlota with rather slightly swollen ends; they are about eylindric and straight 

 or quite slightly curved. Their length is 0-24 — o - 34 mm and the thickness ca. 00053 — o - oo85 mm . b. Micro- 

 sclcra; these are birotulse of two sizes. 1. The large birotulse have at either end eight to twelve 

 teeth, their length is 0-031— <yo45 min , the thickness of the shaft is ca. o-ooiS— o-oo28 n,r ", and the breadth 

 across the circle of teeth o - oo8 — o-on mm . A few developmental forms were seen; they consist of a 

 shaft with a pyramidal swelling at either end, and on these swellings slight ribs are seen. 2. The 

 small birotulae have nine to thirteen teeth at either end, their length is O'OiS — o - 024 mm , the thick- 

 ness of the shaft is ca. o-ooi mm , and the breadth across the circle of teeth o-oo57'" m . Both forms of 

 microscleres occur throughout the sponge, the small ones are somewhat more numerous than the 

 large ones. 



Locality: Station 113, 69 31' Lat. N., 7 06' Long. W., depth 1309 fathoms (bottom temperature 

 ■4- i° C), one specimen. While the preceding species were obtained on bottom with positive tempera- 

 ture, the present one is from the cold area. Among the hitherto described fotroc/iota-s^ecies I. abysst 

 Cart, is the only one from cold bottom, having been obtained at 6i° 10' Lat. N., 2° 21' L,ong. W., at a 

 depth of 345 fathoms with a bottom temperature of -=r i°i C. 



I have here established eight new species of the genus lotrociiota, as it has been impossible 

 to identify any of the species before me with any of the hitherto described ones, all of which, with 

 the exception of abyss/ Cart, and magna Lambe, are also exotic species. As will have been seen from 

 the descriptions, several of the species are chiefly separated by characters found in the microscleres, 

 especially the number of teeth in ancorse and birotulse. Now this feature is no constant one, but 

 varies within certain limits; therefore the numbers of teeth of the different species may pass into each 

 other, so that, for instance, the highest number in one species may be equal to, or a little higher 

 than, the lowest number in another species. Nevertheless I think that the number gives a good 

 specific character, and it is in my material always supported by other characters. Unfortunately, we 

 have only a single specimen of most of the species; perhaps a richer material may somewhat alter 

 the interpretation of the species I have established here, but at present the absolutely most correct 

 thing is to keep the species here established distinct, and I am also inclined to believe that new and 

 richer material will prove them to be constant. The view advanced by Dendy (Proceed, of the 

 Roy. Soc. of Victoria, VIII, 1896, 23) under the mentioning of I. cocciiica Cart, that the Iotrochota- 

 species may all be mere local varieties of Bowerbank's I. purpurea*, will, no doubt, prove to be 

 erroneous, and the author himself so far contradicts it, as in the very place mentioned he establishes 

 a new species. 



To facilitate the general view of the species established or treated here, I give a table of the 

 difference in the spiculation. 



