ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 811 



hdella) ; in the four just named, branches rise from the longitudinal 

 vessels during sexual maturity, and the posterior sucker contains a 

 number of vascular branches. 



In all the Nemertinea the most anterior point of communication 

 of the vascular spaces lies above the proboscidian sheath, the hind- 

 most above the intestine ; in all the blood-spaces are throughout 

 clothed internally with a layer of epithelium, which is always suc- 

 ceeded by a layer of hyaline basal tissue. 



The nephridia of Carinclla are formed by a portion of the lateral 

 vessels, which is distinctly a portion of the blood-space ; a portion of 

 the walls becomes a gland, the function of which appears to be that 

 of conveying the superfluous material from the blood towards a 

 reservoir, the portion separated from the blood-vessel. On each 

 reservoir an excretory duct is developed, and the two so formed lie 

 nearly on the same transverse plane so that, were the animal seg- 

 mented, they would be found in the same segment. The nephridia of 

 Carinella are, clearly, very primitive in character. 



In Carinoma the nephridial system is more highly developed ; 

 there is no nephridial gland, but the function of removing the waste 

 products is transferred to the canals of the system itself; the secre- 

 tion does not seem to be removed periodically, but constantly, inas- 

 much as each epithelio-glandular cell is provided with a long cilium 

 which has an outward direction ; traces of the blood-vessel may be 

 still detected: the tv^o excretory ducts lie in the same transverse 

 planes. 



In the " schizo-type " we may distinguish two longitudinal and a 

 number of transverse canals, so that the arrangement is segmental ; 

 the lower the type the more numerous are the paired ducts. 



In the Hoplonemertinea we again meet with several degrees of 

 complexity in the nephridial system ; from a longitudinal canal on 

 either side there are given off a number of small canals, which send 

 their excretory ducts outwards ; these may be two or more in number, 

 and they vary as to the position which they occupy in the body. 



"The nephi-idial system of all the ISemertea consists of one or 

 more canals, directly communicating or not with the vascular system, 

 provided or not with cilia, and communicating with the exterior by 

 means of excretory ducts. These excretory ducts all lie above the 

 nerve-trunks." The two caecal vessels of the palajo-type, the part of 

 the median vessel in the proboscidian sheath of the other types, and 

 the " membranaceous sacs " have the function of respiring, feeding, 

 and excreting the fluid of the proboscidian sheath. 



Development of Monopora vivipara.* — Prof. W. Salensky's 

 Btudios on this Nemcrtcan have induced him to establish a new genus 

 for the species which was regarded by Uljanin as a Borlasia ; the 

 difl'eroncoH between it and other Nemertinos arc pointed out. Its 

 moht striking characteristic is the opening of the proboscis and the 

 cesophagUH at a common orifice — the atrium j^>rostovdale. 



The ovifcacB were found to bo derived from the connective tissue 



• ArcL. de Biol., v. (1885) pp. 517-71 (3 i-ls.;. 



