151 



ich nicht irre, hat auch Dr. H. von Ih ering irgendwo über ähnliche 

 Befunde an gewissen größeren brasilianischen Nagern berichtet. 

 Auch hier wartet eine nicht uninteressante wissenschaftliche Aufgabe 

 ihrer Lösung. 



Para, 1. Januar 1900. 



5. Preliminary Description of Zygeupoiia litoralis, a New Genus 

 and New Species of Hetet'onemertean. 



By Caroline B. Thompson, B.S., Philadelphia, Penns. 



eingeg. 1. Februar 1900. 



This Heteronemertean was found by me in August, 1899, at 

 Wood's Hole, Mass., in sand a few feet below low water mark. Four 

 individuals were obtained, two of which I have examined by means of 

 serial sections. In life the worms were about four inches long, slender 

 and rounded throughout length, with the anterior extremity tapering 

 to a fine point. Head not separated from body. Eyes and lateral slits 

 absent. 



The essential anatomical structures are as follows. Proboscis 

 -pore at tip of head, subterminal, ventral. Mouth small, round, on 

 ventral surface behind brain. Rhynchocoel extends over entire length 

 of body. Body musculature consists of an outer longitudinal, a cir- 

 cular and an inner longitudinal layer. Blood system, two fine trunks 

 from head region unite in a broadening lacuna from which the dorsal 

 blood vessel arises. The lacuna continues posteriorly, divides into 

 two branches which partly surround the cerebral organs and become 

 the lateral vessels. Slender branches are given off from these and run 

 beneath the intestine. The single pair of nephridia possess each one 

 excretory duct, at the posterior end of the nephridium. Brain near 

 tip of head, surrounds rhynchocoel, lobes spherical, commissures short. 

 Cerebral organs large, well developed, lie at the posterior ends of 

 dorsal brain lobes some distance behind the ventral brain commissure, 

 and nearly surrounded by the lateral blood lacunae. Ciliated canals 

 short, run from anterior end of cerebral organ straight out to the 

 lateral surface of the head, open directly to the exterior. An inner 

 circular muscle layer is developed at the end of the anterior intestinal 

 region. Muscular crosses occur between the circular muscle of the 

 proboscis sheath, and the circular muscle of the body wall. A lateral 

 sense organ (side organ) is present. 



The family Eupolidae, to which Zygeupoiia belongs, is charac- 

 terized by the absence of lateral slits, the canals of the cerebral or- 

 gans opening directly to the exterior or into shallow ventral furrows. 



