Protistplanktoii. 



137 



A. setosa (Cl.) Jori;. n. nom. 

 (Pl. XVIII, fig. Kiil). 



Botnjopyle setosn Ci.. 1.. .!(». |». l'7. jiI. I, Hi;, in a. h. 



The transverse scctiiMi is a short oval, witli the loni^itiulinal 

 axis in the direction of tlio central rod (.sa<,'-ittally). There arc 

 three lar.i;e swellinirs on the nppcr part of tlic slicll (the .,cephalis"'), 

 a dorsal one, between the spines A and D, and two lateral ones 

 on each side extending forwards to the ventral side. 



I earlier confounded this species with Lithomelism setosu and 

 it is entered in the tables undrr this name. It seems however, on 

 the whole, to be very rare. It is interesting' that it seems to occur 

 dui-iny the .sprini;- diatom iiiHow. 



Malang-en, -'■', , is;)'.», o— .lud m., Lille Molla, '/j ISO'.), in the 

 surt'ace. 



T)istrihiiti(»i: Kai-c on the west coast of Norway. Mentioned 

 by Cleve from places in the northern and western Atlantic, as 

 far as to the west of Spitzbergen, hei-e at great depths (76"— 78" 

 N, 15° E — 3" W, deep sea hauls from 325 m. and more, Aug. 

 and Sept. 1898; 71"— 72" N, 21—22" W, hauls from 180 m. 

 and more, .July 1899; 45" N, 49" \\'. high salinity and temper- 

 ature, January 1S99). 



Aeaiithofoi-ys nmbellifera Hck. (?) 

 (PI. XVIII, fig. 107). 



Haeckel L. 84, p. 305, pi. 6, lig. 12. 



Under this name I have entered a form which has the appear- 

 ance of a species of the division Dieijrtida, but is certainly not 

 fully developed. It is remarkable, as also Haeckel's illustration, 

 for a rather large cephalis and a short, bi'oad thorax. The spines 

 in the thorax, protruding from the free brim like long, tine spikes 

 are characteristic. Some of these spines are weaker than the 

 others and are branches of them. The cephalis is well supplied 

 with long, needleshaped byspines. There is also a similar apical 

 spine, which here, as in Lithomelissa, is the spine D and runs in 

 the wall of the cephalis, thus not forming any inner columella. 



ily species ditters from Haeckel's only in the want of by- 

 spines on the thorax. 



This species occurred very rarely and sparsely in the material 

 from the northern coasts of Norway: 'Vi 1899, 40 miles NW of 

 Gaukværø, 0—700 m.; =7i 1899, Malangen, 0—300 m. 



JJhiril/utioii: More frequent on the west coast of Norway, 

 numerous in the Oster Fiord, near Hergen, at a great depth (up to 

 f.oi) m.), "A; 1900. 



Cleve mentions the species from a few places in the Atlantic, 

 west of Ireland and more to the south, as well as from several 

 places far north, to the north west point of Spitzbergen. In these 

 northern places, the species was only found in deep water. Haeckel 

 mentions it from the Azores and the Mediterranean. Hence 

 Cleve coasiders the species to belong to Styliplankton. It seems, 

 however, .judging from the places mentioned where it has been 

 found, to have about the same distribution as Pkctacantha, and is 

 probably boreal oceanic. 



It is, however, quite possible that Haeckel's is a distinct 

 species. 



Helotholas Jøro. n. gen. 



The four primary spines with the ventral, sagittal one. All 

 live protrude as single .spikes, the doi'sal one, A, down on the 



thorax, (he ventral, sauittal • in the neck .stricture, the one 



marked I), on tlir cc|ilialis as an apical spine. 



The lower part of this latter spine is inside tin; wall of the 

 cephalis, while it a little higher up runs in thi^ very wall. It is 

 therefore no genuine columella. 



There is also an axial spine, as in the olliei' .species here men- 

 tioned of the Ci/rtoldcd <;ronp. This axial spine starts as usual 

 fi-om the vential end of the central rod, in the interior of the 

 lattice shell, a little below the neck stricture, and is in elder indi- 

 viduals of J/rh,tliuliis Instricom divided in two. 



The thorax is bi'oadly campannlate. nearly somispheiical. 



H. histricosa Jøro. n. sp. 

 (PI. XVI, figs. 8(j— 88). 



The ventral sagittal .spine about eipial in strength to the others 

 and is directed a little upwards. The primaiy, lateral spines are 

 nearly horizontal, bent slightly downwards; they protrude at the 

 neck stricture, rather far up. The dorsal spine, A. is directed 

 downwards and pierces the thorax rathei- far down. 



Only the dorsal spine. A, runs for a short distance in the 

 very wall of the thorax, the others pierce only tiie wall. 



The cephalis is semispherical, or a little higher, in cross sec- 

 tion circular. The thorax is broadly campannlate. 



The pores are irregular in shape and size, most of them being 

 roundish or oblong, smallest on the cephalis (1 — 16 ;).), largest on 

 the thorax, especially down below on young individuals. Here the 

 brim of the thorax is furnished with numerous, irregularly placed, 

 short spines, which are not true byspines, but only the walls of 

 meshes which are not yet developed. 



On the cephalis and thorax, nai'i-ow needle shaped byspines 

 are scattered, the longest being about e(iual in length to the dia- 

 meter of the cephalis. 



I have not seen any individuals which could i)e supposed to 

 be fully developed. 



The species does not answer well to any of Haeckel's genera. 

 From the genus Lithomelissa, as I have understood it in the species 

 L. setosa, there ai'e such important differences that it does not seem 

 reasonable to place these two forms in the same genus. It might 

 rather be united with the folloAving species. I have not, however, 

 done so, more especially as the definition of Haeckel's genus 

 Dictijophwms requires that there should be three thoracic ribs which 

 are lengthened out to „basal feet'", and this definition may at a 

 pinch be made to apply to the two following species, but not at 

 all to Hdotholus histricosa. 



Rather rare, sparse, in deep water samples. 



Distribution: Seems also to be a boreal, oceanic species. 



DictyopliimnK Eiirb., Hck. 



This genus is by Haeckel made to include rather highly 

 differentiated foi-ms, which probably ought to be kept distinct from 

 the species which I have here referred to it. There does not, 

 however, appear to be any great disadvantage in placing them here 

 preliminarily. 



From these two species, the genus should be defined as follows: 



The four primary spines ai-e present, as well as the ventral, 



sagittal one. The three basal ones (L,., Lj and A) extend from 



the central I'od to the upper part of the thorax, a little below 



