148 EXTRACTS FROM FOREIGN PERIODICALS. 



before noticed with sufficient accuracy. On each side of this tubercle are two 

 elongated openings, somewhat arched, and crescented : each of these openings 

 incloses a tooth {crochet) of a light brown colour, the base of which is directed 

 towards the tail of the animal. These openings enable the worm to suck, and 

 the teeth are to fix themselves more firmly. In fact, every time that I endea- 

 vored to detach a living individual from the spot to which it adhered, I found 

 that the animal's head was severed before it loosed its hold. 



The head of the male, immediately after its immersion in alcohol, has the 

 appearance of a cavity, so that the suction-apparatus is placed upon a hollow 

 surface. No distinct separation is observed between the head and the rest of 

 the body, because the smooth membrane which covers the head extends, plaited, 

 gradually over the whole body. This is again covered by a smooth membrane, 

 thin and plaited ; but the two sexes differ remarkably with respect to this 

 plaiting, more so than as regards that of the anterior parts seen across. 



In the male, indeed, the plaits extend from the head to the end of the tail, and 

 the lateral ridges are neither so distinct nor -so well formed as in the female. In 

 the latter, on the contrary, the plaits disappear entirely at an inch and one-fourth 

 from the caudal extremity, and do not extend over the whole surface of the back 

 as in the male. They are only visible at the sides, and vanish altogether in the 

 region of the ventral cavity. The lateral ridge itself appears not to be wholly 

 uniform in the female, but at the part where the plaits disappeared, the regular 

 points which followed immediately after likewise vanish. 



The ventral surface of the male presents a large white band, across the skin ; 

 it takes its origin near the head, [passes over the middle of the body, and termi- 

 nates close to the tail. It is there the right testicle, for the left is covered by the 

 intestinal canal, which is not seen here, but only at the caudal extremity. On 

 the back, immediately behind the head, are two small spots, sometimes visible to 

 the naked eye ; these are the genital openings, through which the two cirrhi of 

 the male probably pass. Behind these two openings are seen two white flexuous 

 organs ; these are the two testicles, one of which is already seen upon the ventral 

 face. Further back is the anal aperture of the intestinal canal, which is situated 

 at the end of the tail, and which seems to divide the latter. 



In the ventral region of the female, immediately behind the head, are two 

 indistinct blind vessels, which belong to the sexual apparatus, and not, as 

 Rudolphi conceived, to the intestinal canal. Between these vessels are others 

 of a brown colour, describing a sinuous course. They extend nearly to the caudal 

 extremity, and constitute the oviducts ; they are followed by a simple filament, 

 the intestinal canal, which here distinctly divides the tail. 



On the dorsal surface, at the part where the head is slightly arched, are seen 

 the two blind vessels before mentioned, and between them an obscure spot, which 



