Protistplanktnii. 



Isles (also inoiitioiK'il tVum licrr hy ("m;vk. L. Km. [''(hiikI by 

 IIakokel at Mt'ssiiia. 



Seems to 1)0 a soutlicni. tciiipenile. ocoaiiic t'onn. 



AiitlrocyclaM .jr.iu!. n. gen. 



The four primary spines and the ventral sagittal one are pre- 

 sent. The apical spine, D, runs close to the cephalic wall, and 

 finally protrudes as a marginal topswoi-d. tliiclc and larpe. and fur- 

 uished with three broad edt;es. TIumv is. (■onse(iiu'ntly. no distinct 

 columella. 



The three basal spines. A. \.^. and L| p rot I'ude from the upper 

 part of the thorax (the spine A lowest down) like fine needles, 

 wlueii pierce the wall, no part of them being enclosed in it as 

 ..thoracic ribs". The ventral, sanltlal spine also protrudes like a 

 similar needle in the region of the neck. 



There is also a long, inner axial spine, whicli reaches as far 

 down as to the upper part of the abdomen. 



Cfr. the remarks about the i-egion of the nock, under the de- 

 scription of the species. 



I refei-red the following species previously to the genus Fte- 

 rocorys Hck., but I now tind it necessary to separate it from this 

 genus which has strong side swords on the thorax. 



On the other hand, there is probably no doubt that the genus 

 Theoconus Hck. to some extent corresponds to my genus Andro- 

 cyclcis. Thus, Theoconus joris Hck. (L. 86, pi. 69, f. 4) is undoubt- 

 edly of quite the same structure as Androcyclas gamphonycha, the 

 byspines on the abdomen of the latter only excepted. As, how- 

 ever, Haeckel's group Theocyrtida, to which Theoconus Hck. and 

 Theocalyptra Hck. belong, is defined as Tricyrtida without radial 

 apophyses, I have thought it most practical, to avoid confusion, 

 temporarily to erect the new genus Aiidroryrhis. 



A. gainpbonj-cha (Jukg.) 

 (PI. XVII, figs. 92—97). 



Ptcrocorys yamphonyxos Jorg. L. 1)1, p. Sd. 



P. theoconus Jokg. 1. c. P. amblycephnlis .Jihti;. 1. c. 



The region of the neck is very peculiar, not forming any di- 

 stinct stricture between the cephalis and thorax, but a zone where 

 these two .joints gradually pass into each other. This region 

 appears on the dorsal side to lie between two pair of branches from 

 the apical spine, D, namely two dorsal, lateral spines below (corres- 

 ponding to those in the genus AmplmneUssa) and the primary, 

 lateral arches above. These dorsal, lateral spines (from the base of 

 the spine A and the spine D) lie near the hind wall of the ce- 

 phalis. The lower part of the apical spine, D, is here a columella 

 in the region of the neck, but lying near the cephalic wall. 



The length of the abdomen varies considei'ably, probably ac- 

 cording to age; this is also the case with the number of byspines. 

 It is not unusual to find comparatively well developed forms \\-hich 

 are apparently almost or entirely without the characteristic by- 

 spines, but which in other respects diverge so little from the ty- 

 pical forms that they can scarcely be considered to belong to any 

 other species. Therefore I now think that Pterocorys theoconus 

 must be looked upon as a form of this species. 



The other, very short tophorn is very rarely seen distinctly 

 and is probably a more or less accidental formation. &!ometimes 

 strong siliceous edgings are developed on the ujjpei- part of the 



cephalis, and these may bo protrudiiiL;- and in certain positions look 

 like a very broad, short spine. 



Accoi'ding to my experience no limit either can be drawn be- 

 tween Pterocorys yamphonyxos and /'. amblycephnlis. The younger 

 forms seem to answer best to the latter, which is in appearance 

 so difierent to P. yamphonyxos that it is generally ea.sy to keep 

 them distinct. (This is done in the tables). The principal dilfer- 

 ence is that P. amblyccphaUs has a cephalis which is at the u|)per 

 part abruptly cut off and, at the very top, often open. This opening 

 is probably closed latei' on. The tophorn is i.'enerally .shorter and- 

 more weakly developed and the ahdonien short and broad, without 

 distinct byspines, all chai'acteristics which may be explaineil by 

 supposing that P. amlilyrephalis is the younger stage of development. 

 On inviduals which it seemed more coi-rect to i-efer to P. amhlycephalis 

 than to P. yamphonyxos, I have also occasionally seen short and 

 broad byspines in conjunction with a better development of the ab- 

 domen. 



On the best developed specimens of .1. yamplionyclin. the ab- 

 domen is again narrowed below, the sti'ongest set of spines being 

 on that part which is broadest. The byspines are only slightly bent. 



Frequent, in Tranødybet "A 1899, 0—630 m., numerous, other- 

 wise rather sparse and generally only in deep water. 



Distribution : On the west coast of Norway, in deep water, 

 rare. Off the coast of Finmark 73 1901, in a surface sample (S/S 

 Michael Sars cfr. Gran, L. 70, p. 154). Perhaps a temperate oce- 

 anic form. 



Clatlirocycla^ craspedota (Jorg.) Joro. 

 (PI. XVU, figs. 98—100). 



Theocalyptra craspedota .Jukg. L. 91. p. 80. 



The abdomen is a narrow, flat, projecting brim, on well devel- 

 oped specimens having two or three regnlai-, circular rows of meshes, 

 the inner row with small pores. The free side-walls of a I'ing of 

 meshes undei' development will have the appearance of a regular 

 circle of shoi't, radial spines on the abdominal brim. 



The same spines are present as in the preceding genus. The 

 three basal spines pi'otrude similarly as fine needles in the upper 

 part of the thorax (the dorsal spine, A. farther down than the 

 others). The apical spine, D, also here piotrndos with a broad 

 three-edged topsword directed upwards and somewhat backwards. 

 The ventral, sagittal spine protrudes upwards and foi'wards (ven- 

 trally) with a similar, three-edged topsword, which is. however, a 

 little smaller and points obliquely forwards. 



Refer for further details to Jobgexsen, 1. c. 



As the incompletely developed abdomen often exhibits a mar- 

 ginal brim of regular, short spines like those Haeckel draws for 

 species of the genus Clathrocyclas. subgeiuis Clathrocycloma Hck. 

 (L. 86, pis. 08, 59), I have thought it best to I'efer my species to 

 this genus where it seems to have its natui-al place. In doing so, 

 I also think that Clathrocycloma Hck. will be found to have the 

 three basal spines pi-otruding from the upper part of the thoi-ax 

 like fine needles. 



If these needles ai-o overlooked or absent, and no notice is- 

 taken of the spines on the brim of the abdomen, the species accord- 

 ing to Haeckel's system will be a Theocalyptra. 



Hcdicalyptra '•! cornata I5ail. = Th-ocidyjitra c. Haeckel is 

 quite impossible to determine from the veiy imperfect illustration, 



