424 



ORIGIN AND TERMINOLOGY OF THE DEMANIAN SYSTEM 



laimium appendiculatum I observe a tubular glandular vessel, outstretched 

 forward and emptying backward into the vas deferens, that appears homol- 

 ogous with parts of the better known demanian system of the females. See 

 Fig. 2. 



In female nemas the functioning demanian vessels (e.g. pristiurus) elabo- 

 rate a copious, elastic, sticky, non-water-soluble, nearly colorless secretion, 

 possibly utilized ("spun"?) during agglomeration and copulation, and also 

 presumably to protect and preserve the batches of eggs after deposition and 

 during segmentation. 



The demanian organs seem to prevail in mud-inhabiting, and sand-inhabit- 

 ing oncholaims, i.e. those of stagnant habitat; and to be absent or less 

 prevalent in oncholaims living in more thoroughly oxygenated water, on the 

 surface of eelgrass, and among algae, e.g. in Prooncholaimus Micoletzky, 

 1924. 



Origin. As to the primitive nemic tissue from which the demanian vessels 

 may have originated, we seem driven to accept the primitive gonadic tissue as 

 the probable source. The histology of the demanian system reminds one 

 most strongly of the structure of nemic gonads; most of the histological 

 elements known in the demanian system have homologues in the gonadic 

 system of nemas; while on the contrary there is no such tunic, and there 

 are no such forms of nuclei, known in connection with the enteron. 



Equivalent terms of various authors 



DIAGNOSES OF THE GENERA AND SPECIES MENTIONED HEREIN 



ONCHOLAIMINAE Filipjev, 1918 and 1925 



(but without Anoncholaimus, Pelagonema, Anoplostoma, Trilepta, Krampia. 



Filipjevia.) 



