ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 619 



fagcs saw in Branchellion, and may be regarded as being the origin of 

 the more complex arrangement which is seen in the higher Hirudinea. 

 The seminal vesicle is large, and of a white colour ; its efferent canal 

 is more resistant in structure, and is so folded on itself as to take 

 the form of a reversed U ; the ascending is more muscular and less 

 glandular than the descending branch, and has a much wider lumen; 

 the descending branch enters into relation with the efferent canal. 



The spermatophore pouch is ovoid in form, and soft ; that of either 

 side unites with its fellow by a short canal which opens at the male 

 orifice ; it is essentially formed of long unicellular glands, surrounded 

 by a common muscular investment ; the short connecting canal is 

 formed by the invagination of the integument at the level of the male 

 orifice. 



The female apparatus consists of two ovaries, two oviducts, and 

 two accessory glands ; the ovaries are tubular, and often rolled round 

 the vesicles, sometimes even round the nerve chain ; their wall is 

 delicate and transparent, and contains two planes of muscular fibres ; 

 the oviducts are merely prolongations of the ovaries ; the accessory 

 glands give off two or three canaliculi which open into the canal 

 which is formed by the fusion of the two oviducts ; they are soft, and 

 contain a reticulum of muscular and connective tissue in which uni- 

 cellular glands are imbedded ; they are invested in a muscular sheath, 

 by which they are, so far, distinguished from the Platyhelminthes. 



The general disposition of the genital apparatus recalls that of 

 Branchellion and Batrachobdella, with which Pontobdella agrees in all 

 essential points. 



Turbellaria of Lesina.* — In a preliminary communication Prof. 

 L. v. Graff gives an account of a few species. The accelous form 

 which in 1874 he called Gonvoluta cinerea he now calls Cyrtomorpha 

 clnerea ; it is very common at Lesina ; the mouth is in front of and not 

 behind the otoliths, the generative orifices are separate, and the penis 

 is a conical protrusible papilla ; the female orifice is fringed by 

 powerful cilia ; the otolith is imbedded in a protoplasmic process 

 arising from the wall of its vesicle. Enterostoma Zooxanthella n. sp. 

 is one of the smallest of the Turbellaria of Lesina ; it is scarcely half 

 a millimetre long ; its dirty yellow colour is due partly to a brownish 

 reticular pigment of the parenchyma, and partly to the zooxanthella) 

 which are found in its enteric cells, each of which ordinarily contains 

 one to three spherical parasitic algae 0*007-0-009 mm. broad. This is 

 the only known turbellarian in which zooxanthellae are found in the 

 enteric cells, and which so far agrees with the Actinias ; Enterostoma 

 has large pseudorhabdites in its integument, and four black eyes ; it 

 is extraordinarily sensitive to light. In the body-cavity of one 

 individual there was found a young sexless Distomum. 



Anatomy and Histology of Myzostomida.t — Mr. F. Nausen has 

 examined a few species of Myzostoma, of which M. giganleum and M. 



* Zool. Anzeig., ix. (188G) pp. 338-42. 



t * Bidrag til Myzostomernes Anatomi og Histologi,' Ho, Bergen, 1885,80 pp. 

 (9 p]s.) ; English resume, pp. 69-80. 



