ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 437 



adheres to the prostate throughout the entire length of that gland, is 

 covered externally by the serous coat, and consists of a layer of 

 interlacing muscular fibres lined by an endothelium. 



The vas deferens, leading from the ovispermiduct to the penis, is 

 lined by a non-ciliated epithelium which is thrown into folds in 

 H. pomatia (barely perceptible in H. nemoralis), and surrounded by a 

 connective tissue, and this in turn by a muscular layer. The penis- 

 sheath has thick plicated walls ; in this case the folds contain 

 connective and muscular elements ; the epithelium has a surface cuticle ; 

 the folds have a very complicated arrangement in JET. nemoralis. The 

 flagellum has a thin broad fold, consisting entirely of connective 

 tissue clad with epithelium, projecting into its lumen ; its end is 

 imperforate ; the walls agree in structure with those of the other 

 organs. 



The albuminiparous gland is a racemose gland, provided with a 

 single duct. The gland-cells are basally nucleated, and have near 

 their margin a protoijlasmic reticulum containing mucous globules ; 

 the epithelium of the ducts is ciliated ; the main duct acquires 

 muscular and connective-tissue coats on quitting the gland. 



In the efferent canal (Baudelot), the " superior efferent canal " of 

 Moquin-Tandon, the tube is simple, not compound ; it consists of con- 

 nective tissue with a few muscular fibres, and its lining epithelium varies 

 from squamous to cylindrical in different parts ; the nucleus presents 

 the appearance (lately so widely observed in both animal and vegetable 

 cells) of a fibrous reticulum in its interior. The tube is found filled 

 with spermatozoa which tend to issue in a mass when it is cut through 

 (this is probably due mainly to the movement of the spermatozoa 

 themselves). Distilled water causes these bodies to become twisted 

 up ; potash produces a gentle oscillation, and then the filament 

 becomes coiled up, but the outer coat is finally resolved into small 

 granules ; acetic acid causes a less active movement and a similar 

 retraction, the tail gradually becomes less refringent under its 

 action and disappears, the head becomes detached from the filament. 



Organization of Tethys fimbriata.* — E. Hartmann endeavours 

 to add to the numerous details of this Nudibranch's history already 

 known, by describing minutely its movements and its appearance in 

 life. 



In crawling it expands the branchiae, moves the lateral processes up 

 and down, backwards and forwards ; the foot undergoes considerable 

 undulatory changes of form. The head-lobes are generally carried 

 highly elevated, but if they are folded back or along the sides the 

 cephalic expansion with its tentacles drawn in spreads out like a veil 

 on the bottom, justifying the name of veil-mollusc which is applied 

 to this animal. The mouth, lying on the body at the lower side of 

 the point of insertion of the cephalic expansion, can be protruded on 

 the end of a smooth papilla, and is surrounded by short, delicate ten- 

 tacles. Near each of the dorsal branchiae, in the middle line, a wart- 

 shaped prominence is temporarily elevated when the branchia itself 



* SB. Ges. Natnrforscli. Freunde Berlin, 1880, pp. 9-12. 



