POR1FRRA. III. 



49 



Tops., dubia n. sp. (to be described hereafter), a Plocamia, an Eurypon and a Polymastia; another speci- 

 men is sitting on a Pecten-shell, likewise covered with several other species, a third specimen grows 

 on a Brachiop<5d-shell and finally a fourth on an erect Bryozoon. The species forms incrustations of a 

 greatest extent of 25 mm with a thickness of about 0-5 mm . The colour (in spirit) is white or whitish, 

 but with regard to two of the specimens it is stated, that they were deep blue in the living state. 

 The surface is diffusely hispid from rather long projecting spicules. The dermal membrane is a thin 

 and transparent film. Pores and oscula were not observed; some canals or canalicular cavities were 

 seen to shine through the membrane. 



The skeleton. The dermal skeleton; in the dermal membrane there are numerous, but some- 

 what scattered chelae. The dermal spicules form fibres or bundles stretching far down in the skeleton 

 and seen quite down at the base; they stretch in an oblique direction up to the dermal membrane, 

 and above, at the membrane the direction becomes nearly quite horizontal; some spicules are also lying 

 singly, quite horizontally in the membrane. Above, at the membrane the bundles are generally rather 

 strong with numerous spicules. The main skeleton is of the typical construction and consists of basal 

 acanthostyli with the head ends attached to the substratum, the longest styli pierce the dermal mem- 

 brane and project beyond it The skeleton is distinguished by the fact that the styli stand somewhat 

 scattered, considerably more scattered than is commonly the case. At the base there is a distinct 

 amount of spongin, in which the heads of the styli are imbedded; the spongin seems to form a con- 

 tinuous lamella at the base of the sponge. 



Spicula: a. Megasclera. i. The skeletal spicules are acanthostyli which are straight or, 

 especially the larger ones, slightly curved; they have generally no distinct head marked off, or this 

 is only the case to a slight degree, but the dense spinulation at the base gives however the impression 

 of a swelling; they taper evenly into a somewhat fine apex. The spinulation is as usual, the spines 

 being largest at the head-end and radiating, while they are generally reclined on the shaft in the 

 smaller styles. The smallest styles are spined in the whole length, the longer the styles are, the 

 longer a part of the apex is smooth, in the longest styles only the lowermost part is spined, and the 

 spines are here generally small, nearly gritty, and not reclined. The size of the styles varies greatly, 

 the length from 0-107 * about o-8o mml and the diameter of the head is from 0-018 0-034 mm . To be 

 sure there is no principal difference between the styles, but there is a break in size between the 

 longest and those coming next in length, such that the longest do not go below O'53 mni and the small 

 not beyond o'3O mm . 2. The dermal spicules are rather long, straight, slightly polytylote strongyla; 

 they have always one end thinner than the other; the length is 0-32 O'4o mm , and the diameter in the 

 middle is about 0-005 0-007 mm . b. Microsclera; these are chelae arcuatse; they are distinguished by 

 the shaft being strongly, nearly semicircularly curved; there may in this respect be some difference, 

 the chelae may be both more or less curved, but the typical form is near the semicircular curvature; 

 the end parts are relatively small, the tooth and the alae are short and rounded. The length is 

 0-031 0-03 7 mm ; the shaft is somewhat flattened and about elliptical in section, its diameter is, as seen 

 from in front or from the side respectively 0-005 o-oio mm . The chelae occur, as mentioned, numerously in 

 the dermal membrane, but, however, somewhat scattered; they were not observed otherwise in the body. 



') The greatest length cannot be given exactly, as these styles generally have the apex broken. 

 The Ingolf-Expcdition. VI. 3. 7 



