156 



NOTES AND MEMOKANDA. 



cells — one median and two lateral — separated from one another by the 

 fibrous cords. The space between the two latter, which is wider above 

 than below, is probably the remains of the primitive medullary groove. 

 The lateral rows of nerve-cells, although continuous, present accumu- 

 lations at intervals, corresponding to ganglia. These spots are marked 

 in the recent state by patches of violet pigment, from which pro- 

 longations are continued along the nerves. 



The eyes are seated directly upon the brain ; the lens is single, not 

 double as in other species ; the pigment is black. The structures 

 situated just in front of the brain, and described as vesicles by Car- 

 penter and Claparede, were only seen in one specimen, and are in 

 reality pits, possibly of a sensory nature, although no nerve-supply 

 was made out to them. 



One of the most important points in the paper is the interpretation 

 given by Vejdovsky to the anomalous " rosette-like organs " of the 

 parapodia. One of these is situated near the edge of the fin-like 

 expansion of both notopodium and neuropodium ; it is of a bright 

 yellow colour, and consists of five to seven prismatic bodies arranged 

 in a circle. This is all that can be seen in the fresh state ; but after 

 treatment with osmic acid, alcohol, and picro-carmine, the yellow 

 rosette is stained black, and the prisms of which it is composed 

 become very distinct, and are seen to be surrounded by a fine homo- 

 geneous investing membrane ; abutting against their upper ends is 

 seen a convex, highly refracting lens, while at the base of ^he rosette 

 is a clear roundish area, surrounded by a zone of nerve-cells, from 

 which fibres are given ofi" to the pigment of the prisms. The 

 " rosette-like organ " is thus proved to be a parapodial eye : the 

 animal possesses two of these visual organs to each parapodium, over 

 and above the already known cephalic eyes. 



2. Sexual Products and Seminal Ducts. — The ova begin as groups 

 of cells formed on the living membrane of the prolongations of the 

 body-cavity into the parapodia. These groups become detached, and 

 float freely in the perivisceral fluid ; of the cells of which they are 

 composed, one develops at the expense of its sister-cells, and becomes 

 an ovum. No external aperture for the escape of the eggs was ob- 

 served. 



The seminal cells have a similar origin : the ripe spermatozoa 

 escape from the body by the segmental tubes. These organs consist 

 of a tubular ciliated internal portion, opening into the perivisceral 

 cavity by a funnel-shaped aperture with a rosette-like ciliated border, 

 and of a dilated external portion opening on the surface of the body 

 by a rounded aperture. The dilated half of the tube acts as a vesi- 

 cula seminalis. In the posterior part of the body the spermatozoa 

 become aggregated into rounded masses (Samenklurapen), devoid of 

 an investing membrane, but mistaken for testes by Carpenter and 

 Claparede. 



The paper concludes with a discussion of the various species of 

 Tomojpteris and EschscJioltzia, the two genera of Tomopteridfe. 



Abnormal Sexual Organs in the Horse-Leech. — A very curious 

 variation from the ordinary type of generative organs is described by 



