86 Journal of the Asiatic Society of Bengal [February, 1907. 



have been little worked at outside Europe and temperate North 

 America. Kraepelin recognizes four species of the genus,^ 

 P.princepsy P. pMlippinensis^ P. jpolymorpha and P.j>unctata. The 

 last of these has only been recorded from Europe and North America, 

 on neither of which continents has it been taken in many localities ; 

 but I have recently found it in Calcutta. P. jphiUpjpinensis has only 

 been found in the archipelago from which its name is derived ; while 

 forms which may be included in the remaining "species'* have 

 been recorded from most parts of Europe, from many localities 

 in North and South America, from temperate and tropical Asia, 

 and from several parts of Africa and Australasia. 



As Kraepelin*s monograph is in many respects the most com- 

 plete as yet available, it may be taken as a basis for a discussion of 

 the classification of Plumatella ; but any such discussion is bound 

 to have results which are rather negative than positive, until not 

 only the European and North American but also the South Ameri- 

 can, Asiatic and African forms have been more thoroughly col- 

 lected, described, figured and compared. What is said at present 

 is said in a tentative manner, merely to prepare the way for 

 further investigations. I hope to have an opportunity of figuring 

 Indian examples on another occasion. 



The following are translations of Kraepelin's diagnosis of 

 P. jprinceps and P. polymorjphay the two " species" in w^hich he 

 grouped together the whole of the Holarctic forms not included in 

 P. punctata. 



P. princeps : — ** Stem tubular, branching continuously, with 

 creeping and upright lateral offshoots. The latter either simple, 

 branched like a stag's antlers, or compacted together like turf, or, 

 in extreme instances, agglutinated into massive clumps. Ectocyst 

 generally with solid walls, of a deep brown colour and thickly 

 encrusted, with a more or less prominent keel, which usually pas- 

 ses through a broad delta-like area into a very sharply separated 

 soft zone surrounding the aperture. The statoblasts (on a firm 

 support) of two kinds; those surrounded by a riug of air cells 

 elongate, 0*36 — 0'57 mm. long and 0*2 — 5"3 mm. broad ; the relative 

 proportions of breath and length as 1 to 1-53 — as 1 to 1'28 



The sessile form generally larger and broader (O^^-O'Smm. long 

 and 0'3 — 0'4mm. broad), very variable in form, with a delicate 

 serrated margin. Number of tentacles, 42 to 48 (so far as it is at 

 present investigated)," {Beutche Silsswasser Bryozoen, i, p. 319). 

 P. polymorpha : — '' Stem tubular, with creeping and upright 

 lateral offshoots. The latter either simple, branched like a stag's 

 antlers, or compacted together like turf, or agglutinated into 

 massive clumps. Ectocyst generally with deUcate walls, often 

 quite hyaline (especially in the younger offshoots), or straw- 

 coloured, more seldom of a deep brown colour with a sharply 

 separated hyaline zone surrounding the aperture. Keel generally 

 absent, sometimes, however, prominent even in hyaline forms. 



1 For a recent account of the distribution of Plumatella see Zykoff in 

 Zool. Anz. xxv.. d. 181. 



