ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 649 



developed coelom have a proportionally smaller number of vascular 

 branches ; the physiological cause of this appears to be that, in the 

 latter, the ciliated funnels are nearer to a larger quantity of lym- 

 phatic fluid, and so are more easily able to conduct it into the 

 capillaries of the water- vascular system. The integument of Platy- 

 helminths appears to be capable of endosmosis but not adapted to 

 exosmosis ; in consequence of this the received water has to make 

 its way out by special efferent canals. The two species of Micro- 

 stoma described are M. lineare of Oersted, and M. caudatum of Leidy. 



Stenostoma agile is a new species, in which the ciliated pits lie 

 far forwards, and are innervated by nerves from the anterior lobes 

 of the cerebral mass. There are four new species of Mesostoma. 

 M. goHOcepliahim, in which the eyes are reniform and appear to have 

 small lenses, which are not, however, highly refractive. M. ccecum, 

 which has no eyes, is without true pigment, and is only occasionally 

 coloured by its food ; there are no flagella or other tactile hairs ; it 

 was found in mud, under stones. M. pattersoni has a number of cells 

 and cell-spheres in its perienteric fluid, and these are driven about by 

 every contraction of the body- wall ; the water-vascular system is 

 particularly easy to detect, and the ciliated lobes are most numerous 

 in the cephalic region. The interesting peculiarity of M. viviparum 

 is denoted by its specific name ; there appears to be no vitellarium, 

 the ovary is not well defined in area, the ova lying in the parenchyma, 

 near the genital orifice. There is no sign of any bursa copulatrix or 

 receptaculum seminis. All the embryos of one mother appear to be 

 at about the same stage in development. The author hopes to 

 describe the developmental history at a future time. True viviparous 

 Turbellaria are extremely rare, none being known in Europe, though 

 two have been described by Girard from North America. Chlorophyll- 

 bodies are richly developed, and the author refers them to the pre^ 

 sence of algae ; he goes so far as to correlate with their presence the 

 absence of a vitellarium, and the habit of viviparity, thinking that the 

 embryos find the maternal body a suitable place for development in 

 consequence of the abundance of food and oxygen. 



Gyrator (?) alhiis n. sp. is the name given to a sexually immature 

 species. 



In Vortex pinrjuis n. sp. the testes are irregular sacs, and the 

 penis is completely separated from the seminal vesicle ; the sperma- 

 tophores are fairly simple in structure ; the vestibule of the generative 

 organs is so spacious as to serve for a uterus, in which the ova are 

 invested by yolk after fertilization. V. hlodgetti n. sp. has the copu- 

 latory organ provided with six spines. 



Flagiostoma (?) pjlanum is the name of a new species which is 

 founded on a single example, with an extensile terminal mouth, and 

 with a spacious intestine which is provided with a pair of diverticula ; 

 these are not mere constrictions as in some species. Spaces or 

 lacunar in the body-parenchyma are very rare. 



The author takes the opportunity of describing Tctrastemma 

 aquarum dulcium to express his belief that the four groups of 

 Rhabdocada, Triclada, Polyclada, and Nemcrtinea are of the samo 



