THE PLANKTON OF THE FAEOE CHANNEL AND SHETLANDS. 347 



layer of granular protoplasm, from which arise numerous pseudopodia 

 which ramify through the calymma, and are connected with the extra- 

 capsular bodies and spaces. The yellow cells (xanthellae) are numerous 

 — 12 to 20 or 30 in an individual — and where the central capsule is 

 dividing many of these appear to be undergoing the same process. 

 They have an average size of '02 mm. Extracapsular bodies are numer- 

 ous, and contain granular protoplasm, and often what look like small 

 fat drops, but osmic acid fails to stain them. 



The description of this Collozoum may be briefly put as follows :— - 

 Colonies, long and thin, more or less elongated, not segmented. 

 Individuals, "OO-IO mm. in diameter, round, with thick pseudopodia, 

 central capsule very fine, " assimilation plasma " (Brandt) absent (?) ; 

 two to four oil drops of bright yellow colour occupying the centre or 

 major portion of the capsule ; yellow cells (xanthellae) numerous, 12-30, 

 situated in the " pseudopodia mother-bed " round the capsule. 



Distribution : In surface waters round the whole coast of Shetland, 

 and in the Faroe Channel. 



The species under discussion — a more detailed description of which 

 is reserved for a future occasion — while possessing some of the charac- 

 ters of C. fulvum, much resembles C. pelagicum in the possession of 

 yellow oil drops, but differs from the latter in the great number of 

 xanthellae, which in C. pelc(gicu7n are only 2-6 per individual. The 

 size of the individual agrees more with C. fulvum. We must bear in 

 mind the caution given by Brandt in his painstaking monograph on 

 the colony-building Eadiolaria, that it is very difficult to recognise the 

 various Collozoums in their young stages. Besides C. incrme, 2)dagicitvi, 

 fulvum, hertivigii, Brandt describes eight examples of skeletonless 

 sph?erozoida which do not conform with any of the above, some re- 

 sembling ^;c/«^i«Mn, others incrme, others having apparently distinct 

 peculiarities. It may be remarked that Haeckel's description of Coll. 

 pelagicum differs remarkably from that of Brandt,* and the latter, 

 whose careful and minute descriptions, as I have found from experience, 

 appear to be extremely accurate, remarks that under Coll. inerme both 

 Haeckel and Her twig have confused many different kinds. This northern 

 species of Collozoum, which is certainly not C. incrme, appears to more 

 nearly resemble C. pelagicum than any other kind. 



Quite recently (September, 1901) I have found in Scapa Flow, in 

 Orkney, day after day for a fortnight, quantities of a Collozoum which 

 differs greatly from the organism just described. A detailed study 



* Haeckel {Challenger Report) describes C. pelagicum as having small, irregularly 

 shaped central capsules, transparent and without oil globules, often many extracapsular 

 vesicles in the jelly body. Membrane very thiu and delicate. Diameter of central 

 capsules, '02- 'OS mm. 



