638 F- F. LAIDLAW. 



body is constricted off to form a kind of proboscis or pre- 

 oral lobe [Pr.], which is non-retractile. Immediately behind 

 this constriction lies the " mouth " mid-ventrally (M.). There 

 are two genital openings, also mid-ventral, lying close together 

 at about a fifth of the total length of the body from its 

 hinder end; the male opening (c?) is in front of the female 



The surface of body is evenly ciliated throughout. In 

 some cases there is a disc-like flattening at the hinder end, 

 but this is only exceptionally present. On the sides of the 

 proboscis are papillae which resemble in appearance those 

 figured by von Graff for Proxenetes tuberculatus, v. Gr. 

 [2] ; a few of these papillse are present at the hinder end of 

 the body. 



The mouth leads through a well-developed pharynx {Ph.) 

 into the spacious gut cavity {En.), which sends forward a 

 median diverticulum {A. d.) into the proboscis, terminating 

 immediately behind the brain {Br.), which lies at about the 

 middle of the proboscis. On either side of this anterior 

 diverticulum lies a rounded testis {Te.). There is a well- 

 developed penis provided with a complicated armature {Pe.) 

 lying in front of the male opening. Into the penis open a 

 pair of vesiculas seminales {V.s.) and a number of unicellular 

 glands (Gl.). The female aperture leads into a bursa senii- 

 nalis {B. s.) provided with a chitinous appendage (C/i. a.). 

 The single ovary {Ov.) lies at the hind end of the body nearly 

 in the middle line ; it is somewhat curved, and the eggs are 

 progressively riper from behind forwards. In front of the 

 ovary is a structure which may be called the receptaculum 

 seminis {B. s.). 



The pigmented eye-spots found in many Rhabdocceles are 

 here absent, and there is no otolith. 



In several respects this little creature differs from any 

 known forms; its nearest allies appear to be found amongst 

 the Mesostomidas and Proboscidse as defined by von 

 Graff [2], but as it cannot well be referred to any known 

 genus of either of these families I have found it necessary 



