324 Dr. L. Bohmig on the Excretory Organs dec. 



G. damarensis, a wliite-spotted form, certainly occurs in 

 Angola, for the British Museum contains a specimen collected 

 there by Dr. Welwitsch, and some of the forms may be referred 

 to this species ; but most of the specimens are rather young 

 for determination. G. hottentottus, G. damarensi's, and 

 G. Socagei'y having the naso-frontal suture of somewhat the 

 same pattern, the skulls are difficult to distinguish when 

 young. The occipital spot is undoubtedly a variable cha- 

 racter, as I find in normally unspotted forms, such as G. Nim- 

 rodiy an occasional specimen with a small white spot, and in 

 the normally large-spotted form, G. Darlingi^ an occasional 

 specimen turns up with only a very small white spot; thus it 

 may be possible outwardly to almost perfectly match speci- 

 mens of these two otherwise very widely distinct species ; 

 this only shows how necessary it is to have far larger series 

 of these animals before we can say whether age, sex, or 

 season has anything to do with their varying exteriors. 



XXXVI. — On the Excretory Organs and Blood-vascular 

 System of Tetrastemma graecense, Bohmig. (A Provi- 

 sional Communication.) By Dr. L. BoHMiG, of Graz *. 



The freshwater Nemertine which I observed in the year 

 1892 in a reservoir in the Botanical Gardens here I have 

 again discovered in greater numbers in the same place, and 

 have been enabled to submit it to closer investigation. I 

 devoted my attention especially to the excretory and sexual 

 organs, and now give a short statement of some of the results 

 of my researches. 



Although the plates for ray memoir on Tetrastemma 

 graecense were finished a considerable time ago, the publica- 

 tion of the paper itself has been greatly delayed, partly in 

 consequence of my professional duties and partly owing to 

 the examination of a land Nemertine found in the hothouse 

 of the local Botanical Gardens. 



In specimens to which a moderately strong pressure has 

 been applied there is readily recognizable on each side of the 

 body a system of clear ramifying canals, from 4*26 to ll"36yu. 

 in diameter, which communicate one with another and per- 

 meate the animal throughout its entire length. In the anterior 

 extremity of the body, in the region of the brain and in 

 front of it, I observed only a single canal of larger size, which 

 was disposed in manifold sinuosities and loops, and ultimately 

 became broken up into a fine close-meshed network of very 

 small canalicules ; at the posterior end of the body I failed 

 to discover a terminal plexus of this kind. Into the coarser 



* Translated by E. E. Austen from the * Zoologischer Auzeiger,' 

 Bd. XX. No. 523 (February 1, 1897), pp. 33-36. 



