46 PORIFERA. III. 



Spiciila: a. Megasclera. i. The skeletal spicules are acanthostyli, they are straight, more 

 rarely slightly curved, with a distinct, globular, but however only slightly swollen head. The spinu- 

 latiou is dense, consisting of large, more or less reclined spines; on the head, where the spines are 

 largest, they radiate straight out, and also on the lowermost part of the shaft; the larger styli 

 become dispersedly spined outwards and have a smooth apical part; the smaller ones are spined in 

 the whole length, but they have often, however, the spines somewhat dispersed towards the apex. 

 The length is o - io 0-30 """, and the diameter of the head is 0-014 0-028"""; the styli are not divided 

 into two groups of size. 2. The dermal spicules are straight strongyla; they are of the same 

 thickness in the whole length and more or less polytylote; one end may be quite slightly swollen. 

 The length is 0-29 037 mm and the diameter 0-005 0*007 mm . D - Microsclera are chelae arena tee, they 

 are rather small and slender, the tooth is narrowly elliptical, the alas are connected with the shaft in 

 their whole length, viewed from in front they are only slightly incised below, the chela thus 

 approaches to the palmate chelae; the shaft is slender and evenly but not much curved. The length 

 is 0-033 0-038 mra , an d the diameter of the shaft 0-002 """. The chelae occur in somewhat great numbers 

 in the dermal membrane. 



This species in its acanthostyli somewhat resembles Koehleri, but it has larger strongyla, 

 and more slender chelae of another shape; from baculifera Tops, it is distinguished by the chelse. 



Locality: Station 105, 65 34' Lat. N., 7 31' Long. W., depth 762 fathoms (bottom temperature 

 -- o 8 C); station 125, 68 08' Lat N., 16 02' Long. W., depth 729 fathoms (bottom temperature -=- o 8 C.); 

 the species is thus limited to the cold area. The localities lie North and North-east of Iceland. 



4. H. lamina n. sp. 

 PI. V, Fig. 8. 



Incrusting ; surface smooth. Spicula: megasclera; the skeletal spicules acanthostyli with a rather 

 small, globular head, spined in the whole length, but the spines in the longer spicules "very dispersed 

 towards the point, o~i2 o-jj mm , not divided into two groups; the dermal spicules strongyla, o~22 o - j6"""; 

 microsclcra small chela arcuata of a shape reminding one somewhat of palmate chela;, tro28 mm . 



Of this species we have five specimens, three growing on two different Bryozoa, one on a 

 stone and one on a living Brachiopod; it has a greatest extent of 10 17 mm , the thickness is about 

 0-5""". The colour (in spirit) is greyish white. The surface is smooth, without projecting spicules. 

 The dermal membrane is a rather thin, but somewhat solid membrane, resting on the skeleton below. 

 Some canals were seen shining through the membrane. 



The skeleton. The dermal skeleton consists of bundles and fibres of dermal spicules, stretching 

 from the lower part of the sponge up to the membrane; they have a more or less oblique direction, 

 and below the dermal membrane they may run as horizontal or nearly horizontal fibres, but there is 

 no skeleton in the dermal membrane itself; the fibres have many spicules alongside, but they are 

 however not specially thick. The main skeleton is formed in the ordinary way, it is somewhat dis- 

 persed. At the base an amount of spongin is found in which the heads of the acanthostyli are 

 imbedded. 



