12 THE ZOOLOGIST. 



the female the organs appear in the same position, but the 

 anterior lateral tentacle remains as the median — all being flat- 

 tened, a fact which M. Malaquin considers is corroborative of 

 his interpretation of the homologies of the bifid organ in the 

 male. In the advanced free male bud (Polybostrichus, Muller) a 

 short pair of lateral posterior tentacles occur in front of the 

 dorsal eyes. Cylindrical tentacular cirri (dorsal and ventral) 

 are present in the post-cephalic segment, whereas in the female 

 only a single foliaceous one exists. The dorsal and ventral eyes 

 appear as mere pigment-touches, and gradually attain greater 

 complexity. The structure of the feet in the buds of different 

 sexes in the main corresponds, the best developed organs being 

 anterior, the most rudimentary posterior — that is, the most 

 recently formed segments (from the formative zone) possess 

 imperfectly developed feet. In the fully formed foot the flattened 

 cirrus occurs dorsally, then follow the long swimming bristles, 

 while the ventral division has bristles with short bifid tips 

 differentiated from the shaft. In the males the first four 

 segments are devoid of bristles, and in these the special 

 elements are developed. In the females the natatory bristles 

 commence on the first bristled segment, though occasionally 

 they vary. 



By and by the best developed buds, which show by their 

 vigorous motions their independence, break off posteriorly, and 

 swim freely in the water, the males — consisting of about thirty 

 setigerous segments— being known to zoologists (before Alex. 

 Agassiz cleared up the subject) under the name Polybostrichus, 

 and the females — of about thirty-five segments in all — under 

 the name Sacconereis. In the latter a pouch, occupying fifteen 

 or sixteen segments of the median ventral region, is formed by a 

 secretion from the epidermal glands, and in this the eggs are 

 carried until they are developed into larvae. 



In Autolytus Edwardsii, De St. Joseph, several varieties of 

 budding occur. Thus Malaquin found a cephalic thickening be- 

 tween the fortieth and forty-fifth segments, such thickening 

 occurring therefore in an old segment and not in a new.* In 

 front of the developing head is a zone of proliferation pertaining 

 to the nurse-stock. After the formation of the head (which is 



* In others between the twenty-fifth and twenty-eighth segments. 



