ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 597 



transverse straight canals are given off, wliicli raay partly serve as efferent, 

 and partly as collecting canals. The long canals lie so deeply in the 

 parenchyma, that it is hardly possible to observe them except in sections. 

 The plexiform canals and the ciliated funnels must, however, be studied in 

 living tissue ; the latter are connected with the former by canals of varying 

 length in which there seem to be no cilia. 



The nerve-trunks vary in structure in diflferent parts ; the longitudinal 

 trunks are connected by transverse commissures which are very thin, and 

 often branch ; the author was also able to detect these commissures in 

 specimens of Bijpalium Liana. In addition to these there are strongly 

 arched nerves, which form a plexus under the skin, which is best developed 

 on the head and in the anterior part of the body ; the ganglionic cells are 

 large, and have very large nuclei, with two or three jirocesses. The longi- 

 tudinal nerves are connected with one another at the hinder end of the 

 body. In the cephalic region there is a flattened brain, the formation of 

 which is clearly due to the union and increase in size of the longitudinal 

 trunks ; from this region strong nerve-branches pass to the pits found at 

 the anterior end ; the nerve-fibrils are thick, and give off from their ends 

 fine prolongations which extend outwards between the cells of the epidermis. 

 Eyes are present in large numbers, and form a zone three or four rows deep 

 at the margin of the head ; they are also found at the sides of the body as 

 far as its posterior end. The largest eyes lie just behind the head. In 

 structure they agree closely with those of the other Triclades, and they are 

 supplied with nerves from the superficial plexus ; in some cases a ganglion- 

 like swelling was noticed at the sides or in front of the eyes. 



The whole body is provided with cilia ; between the ordinary epithelial 

 cells there are here and there groups of more delicate, rod-like cells, which 

 may possibly be sensory organs ; the rhabdites are mostly small and 

 spindle-shaped, but not a few are filamentar and more or less rolled on 

 themselves ; both kinds are found in the same cell. 



In B. Diana an encysted Nematode was observed, and in the unpaired 

 exterior branch there was a gastropod radula. Fuller accounts with 

 illustrative figures are promised. 



Function of Uterus or Enigmatic Organ in Fresh-water Dendrocoela.* 

 M. P. Hallez appears to agree with Ijima in thinking that the function of 

 the so-called uterus of fresh-water dendrocoele planarians is that of a gland 

 which secretes the substance that forms the envelope of the cocoon. The 

 organ called enigmatic by O. Schmidt, and muscular glandular organ by 

 Ijima, appears to M. Hallez to act as a pump or piston which drives into 

 the cloaca the male elements ; and it is not impossible that it also serves to 

 distribute the fertilized ova, and to expel the cocoon. Planaria polychroa, 

 w^hich is without this organ, has muscular fibres in the cloaca and near the 

 orifice of the uterine canal ; these appear to take the place of the absent 

 organ. 



In the rhabdocoelous planarians, and especially in Vortex, there is an 

 organ which appears to be similar to the enigmatic organ ; it is known as 

 the bursa copulatrix, and the same name might well be applied to the organ 

 in the Planarije. 



5. Incertae Sedis. 



Balanoglossus Larva.f — Mr. W. F. E. Weldon describes a larva, not 

 unlike that described recently by Mr. Bateson, which has, however, a very 

 different history. After the development of the gill-slits there appears to be 



* Comptes Kentlus, civ. (1SS7) pp. 1529-32. 



t Proc. Roy. Soc. Lond., xlii. (I8S7) pp. 146-50. 



