404 SUMMARY OF CURRENT RESEARCHES RELATING TO 



municating ■o'ith a central canal, which dilates before ending near the 

 oviduct. The structure of the gland recalls that of Diplozoon. (e) The 

 irregularly conical shell-gland, prolonged superiorly, and borne on a short 

 broad stalk. It is covered with a connective-tissue membrane, lined by a 

 thick epithelium, and often contains only a single egg as in several Poly- 

 stomeee. (/) The adjacent uterus is first expanded, then narrowed, again 

 dilated and again contracted before opening in a small depression, protected 

 by a musculo-cutaneous fold. (^) In the region occupied by the oviduct, 

 the albumen duct, the uterus, &c., there is a small blackish tract directed 

 dorsally, and apparently representing the canal of Laurer, though without 

 visible external aperture. 



(Ji) The seminal fluid passing from the ejaculatory duct probably flows 

 into the gynaecophorous canal, and is led by the ventral groove in the 

 female to the opening of the uterus. The almost permanent copulation 

 secures fertilization. 



Sexual Characters and Generative Organs of Micro stomida.* — Herr 

 D. liywosch has examined Microstoma lineare and finds that it is not 

 thoroughly bisexual, and indeed he is inclined to regard it as a completely 

 hermaphrodite form ; solitary males were never observed ; in the anterior 

 individual of a chain male generative organs were never found. The 

 generative organs do not appear to become completely matured till an 

 individual leaves the chain. The generative organs are ventral in position, 

 and the female in front of the male ; the author diifers from Vejdovsky in 

 regarding the testes as always single and never double. The penis varies 

 in form, having sometimes the appearance described by Schultze, and some- 

 times that described by Grafl". The ovary is a club-shaped tube formed by 

 a structureless membrane and a number of egg-cells, not divided by con- 

 strictions ; the ova are always developed from the median cells, and as 

 they grow the number of bounding cells increases ; these are used as food 

 for the egg. The ovary passes into a distinct efferent duct, which opens 

 on the median ventral line ; the duct is invested by small cubical cells 

 which are strongly ciliated, and by tubular granular glands. The presence 

 or absence of sexual forms in autumn, as to which Schultze and Graff are 

 in disagreement, appears to depend on climatic conditions. 



Anatomy of Schizonemertini.t — M. E. Saint-Loup gives an account of 

 the cephalic pits of Cerehratulus viridis, and Ophiocephalus Elizahethse ; he 

 describes in the former a pillar which traverses the central mass ; in it 

 there are a longitudinal and two lateral canals which are so disposed that 

 the cavity which contains the substance impregnated by haemoglobin com- 

 municates with the exterior by the lateral ducts as well as by the cephalic 

 pits ; all the canals, with the exception of one which leads to the pharynx, 

 are ciliated. In OpMocephalus Elizahethse the communications between the 

 " pericerebral cavity " and the exterior are similarly arranged, but there 

 does not seem to be any duct leading into the pharynx ; the ducts end in the 

 hajmoglobinoid substance, and are there enveloped with strongly coloured 

 brownish-yellow granulations; so that an excretory glandular formation 

 appears in the tissue to which respiratory functions are ascribed. In neither 

 of these two forms does the author find the hepatic tissue noticed by M. 

 Marion in Borlasia Kefersteinii, nor the uric acid concretions which have 

 been observed in Tetrastemma flavidum ; there are, however, granulations of a 

 dark brown colour abundantly developed in some parts of the digestive tract. 

 It seems, therefore, that Nemertines differ as to the localization of elements 



* Zool. Anzcipr-, X. (1887) pp. Oti-O. t Complcs Eciidus, civ. (1887) pp. 237-9. 



