152 



No muscular crosses in the proboscis. Head gland present. Bürger 

 (Die Nemertinen des Golfes von Neapel, 1895) places in this family 

 two genera, Eupolia and Valencinia. A third genus Parapolia has 

 been described by Dr. Wesley R. Coe (Descriptions of Three New 

 Species of New England Palaeonemerteans. Trans. Connec. Acad. 

 Vol. IX. June 1895). 



Through the kindness of Dr. C o e I have had the opportunity of 

 making a careful study of the preparations of his type specimen Para- 

 polia aurantiaca, and I wish here to express my thanks to him for his 

 courtesy in lending me this material, which has been of great value 

 especially from a comparative standpoint. 



Comparison of Zygeupolia with Eupolia, Valencinia and Para- 

 polia. 



I. Eupolia resembles Zygeupolia in 1) position of proboscis pore, 

 2) rhynchodaeum, 3) essential structure of blood system, 4) nephri- 

 dia, 5) general structure of nervous system, 6) proboscis musculature. 

 Eupolia differs from Zygeupolia in 1) cutis (no inner connective tissue 

 layer in Zygeupolia), 2) head gland (absent in Zygeupolia), 3) length 

 of rhynchocoel, 4) cerebral organs, 5) ciliated canals. 



II. Valencinia resembles Zygeupolia in 1) length of rhynchocoel, 

 2) blood system, 3) cutis, 4) ciliated canals. Valencinia differs from 

 Zygeupolia in 1) position of proboscis pore, 2) rhynchodaeum, 3) ne- 

 phridia, 4) proboscis musculature, 5) brain commissures, 6) cerebral 

 organs, 7) head gland (absent in Zygeupolia). 



III. Parapolia resembles Zygeupolia in 1) length of rhynchocoel, 

 2) cutis, 3) absence of head gland. Parapolia differs from Zygeupolia 

 in 1) position of proboscis pore, 2) rhynchodaeum, 3) blood system, 

 4) nephridia, 5) position and structure of brain, 6) position and 

 structure of cerebral organs, 7) ciliated canals, 8) proboscis muscu- 

 lature. 



Zygeupolia is characterized by certain structures that so far as I 

 am aware have not been described for any other Heteronemertean. 



1) A layer of inner circular muscle in the anterior intestinal 

 region. This is formed by the continuation ventrally of the circular 

 muscle of the proboscis sheath so as to surround the intestine. This 

 layer soon disappears but it is clear and distinct over its short extent. 



2) A crossing of muscle fibres from the circular muscle of the 

 proboscis sheath to the circular muscle of the body wall. This crossing 

 occurs throughout the greater part of the body, and causes the probos- 

 cis sheath to appear as if suspended by a fine thread from the circu- 

 lar muscle of the body wall. 



