136 



E. Jørgens 



as the development of the thorax progresses, the meshes being 

 formed between these spines. Is is possible that var. belonophora 

 JøEG. 1. c, pi. i, f. 22, is the fully developed form, and that its 

 marginal spines are therefore permanent. 



Frequent, mostly in deep water samples, sometimes — but rarely 

 — in the surface. Rarely at all numci'ous. 



Distribution : Belongs to the most frequent Bad'wlarid on the 

 west coast of Norway. 



L. laticeps Jørg. n. sp. 

 (PI. XVL fig. 84). 



As yet, I am only imperfectly acquainted with this species 

 which seems related to L. thorncites Hck. and L. mediterranea J. 

 MtJLL. It differs from the preceding one in having a larger eephalis, 

 which is broader and more obtuse, and by the want of byspines. 

 Neitlier does there appear to be any other protruding spines than 

 the principal ones, with perhaps a couple of branches. 



The thorax has no marginal byspines beneath. The pores here 

 on the lower margin are larger and the walls thinner, so that pro- 

 bably the individual illustrated is not yet fully developed. 



Very rare and only singly: Sea off Røst, "/s 1899, 0—900 m. 



Distrihution: I have seen it in a deep water sample from the 

 sea between the Færø and Shetland Isles (cfr. above, p. 128). 



i. bystrix Jøkg. 

 (Pl. XVI, fig. 85). 



Jørgensen L. 91, p. 8.3. 



Cephalis not very high, finally, by the development of secon- 

 dary, outer arches in the region of the neck, a broad semisphere, 

 which is half of it sunk into the thoi-ax. 



The thorax is above campanulate, below cylindrical, with two 

 distinct, lateral indentations in the upper part. 



In the region of the neck in younger individuals, there are 

 large holes, which later on are, to some extent, closed, by the 

 development of outer arches between the lower part of the cephalis 

 and tlie upper part of the thorax. The pores outside this region 

 of the neck are roundish, of very varying size, being smallest on 

 tiie upper part of the cephahs. 



On the whole, there appears to be the same spines as in L. 

 setosci, but fewer really protruding ones from the inner skeleton. 

 The thorax here too appears to be similarly formed to that of L. 

 setosa. from strong, obliquely downwards pointing byspines on the 

 primary arches. A number of such obliquely protruding byspines 

 ai'e also seen in tliis species in tlie region of the neck. In addition, 

 there are also numerous, needle-shaped byspines on the cephalis 

 and the upper part of the tiiorax, and these, on a broad part of 

 the shell, between the cephalis and thorax, dcvelope fine, connecting 

 beams, covering the large neck openings. 



The region of the neck will here, in this way, be sin-rounded 

 by a covering which causes the cephalis finally to be half (oi' 

 wholly?) sunk into the thorax. This outer covering is chiefly 

 formed from byspines on secondary arches. 



Cephalis 22 [j. broad, thorax 45—50 n broad, 'f he licJLiht of 

 the thorax in the foi'ms occurring in my material 34 — 40 |).. In 

 these forms, which most probably were not fully developed, the 

 brim of the thorax was provided beneath with short irregular 

 spines, which no doubt are flic walls of meshes in ])rof'css ol' devel- 

 opment. 



It is a question whether this species should not be more cor- 

 rectly separated from the genus Lithomelissa. But as I have not 

 as yet had an opportunity of studying the inner skeleton more 

 carefully, I will, for the present, retain it in the genus in which 

 I originally placed it. 



Very rare and occurs only sparsely: '''A, 1899. 40 miles 

 NW of Gaukværø, 0—700 m.; "Vs 1899, the Tys Fiord I, 0—700 m. 



Distribution : Also very rare on the west coast of Norway. 



Anipliiineli^sa Jørg. n. gen. 



This genus in outward appearance is similar to Lithomelissa, 

 but its structure is principally different. It has the most important 

 spines of the Campylncnntha type, namely the four primary ones, 

 A, D, Lj. and Lj, one venti-al, sagittal spine, and two strong 



lateral, dorsal ones, rising from the base of the spine D, which 

 here, as in Lithomelissa, appears as a protruding, apical spine. 

 The primary arches too are strongly developed, the veuti'al arch, 

 namely, as well as the right and left lateral arches (cfr. Plecta- 

 cantha) all as arches inside the cephalis. To these come a 

 couple of strong arches from the dorsal, lateral spines to the 

 primary, lateral arches, also situated inside the cephalis, near 

 its sides. 



These strong inner arches are all connected outwards with 

 the lattice shell, by means of strong, supporting beams which, for 

 the most part, protrude on the exterior, as tine, long spikes. 



This peculiar form is only distantly related to the others in 

 my material. In structure it is unmistakably similar to Phorm- 

 acantha hystrix; but there are, nevertheless, as far as I have 

 hitherto been able to see, important differences in the structural 

 type. The distinctly enclosed columella (the spine D) is charac- 

 teristic; it shows, from the dorsal side, two basal, obliquely down- 

 wards pointing side branches, the dorsal, lateral spines, and higher 

 up two obliquely upwards pointing ones, the usual primary branches 

 of the spine D. Probably the two strong arches from the dorsal, 

 lateral spines to the right and left, primary, lateral arches coi're- 

 spond to the comparatively strong apical arches, which in Phor- 

 maaantha hystrix extend from the primary branches of the apical 

 spine A to the lateral ai'ches. In this case, the dorsal, lateral spines 

 might be considered to be, centrally displaced, primary branches of 

 the spine A, and this answers to their direction. 



The genus Amphimelissa then has an inner, incompletely 

 latticed cephalis, surrounded by a lattice shell, which immediately 

 continues downwards as a thorax. 



The rather intricate course of these inner arehes and skeleton 

 parts here, as in the genera Lithomdissu and Acanthocurys, is diffi- 

 cult to trace in its details, as the outer lattice shell generally 

 conceals them. So there are in tliis genus, as in the other two 

 above mentioned, several structural details which require closer 

 investigation. So nmch is, however, certain, that no satisfactory, 

 natural system of classification i\n- the Cyrtoidea group can bo 

 formed, unless the necessary consi(l(>i-iition is paid to these inner 

 skeleton parts. 



The genus Amphimelissa ought undoubtedly to be kept distinct 

 from the peculiar, irregular forms which form Haeckel's division 

 Botryodrii. 



