THE DEMANIAN VESSELS IN NEMAS OF THE 

 GENUS ONCHOLAIMUS 



With Notes on four new Oncholaims* 



CONTRIBUTIONS To A SCIENCE OF NEMATOLOOY XXIV 1 

 BY N. A. COBB 



Continuing the work of deMan, 1884, and zur Strassen, 1896, observations 

 have been made on Ad&ncholaimus fuscus (Bastian), Metoncholaimus pris- 

 tiurus (zur Strassen) and other Oncholaims (listed on p. 425) with particular 

 reference to the system of tubular organs discovered by deMan. Building 

 on the foundation laid by these eminent observers, it has been possible to 

 define the demanian system, and, within limits, assign it a function. The 

 following definition and table of homologous terms, together with the accom- 

 panying text appreciably advance our knowledge of this remarkable system 

 of organs. 



DEFINITION 



Demanian Vessels: In adult female nemas (Oncholaims) a complicated 

 double system of efferent tubes; connecting, (1), with the middle or posterior 

 part of the intestine through an osmosium (see p. 428), and (2), with the 

 uterus (or uteri); these two efferents being confluent at a special glandular 

 "gateway," the uvette (see p. 427), and emptying thence backward and 

 outward, through one or two ducts having more or less moniliform affluent 

 glands (see p. 426, Fig. 1). Normally, the ducts lead to exit pores in the 

 body wall, usually laterad, one or more on each side, near the base of the tail. 



In certain cases at least, apparently homologous tubular organs connect 

 with the gonad of the male near the beginning of the vas deferens. For 

 example, in Metoncholaimus pristiurus, Adoncholaimus fuscus and Oncho- 



* Investigations carried on in part at the U. S. Fisheries Biological Station, Woods 

 Hole, Mass. The abbreviations used are mostly self-explanatory; e.g. onch dsl, (on- 

 chium dorsale), dorsal tooth. Full list of abbreviations on p. 341. 



1 Reprinted from the JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES, Vol. 20, 

 No. 12, June 19, 1930. 



423 



