176 Dr. E. Greeff on Autolytus prolifer. 



place, the definitely marked generic character ; secondly, the 

 relation of the hud or shoot to its primary individual, together 

 with the connexion of Sacconereis and Polybostrichus with 

 Autolytus ; and, thirdly, some remarks upon the species hi- 

 therto chiefly investigated, but still very unstable as regards 

 its accurate determination, namely Autolytus prolifer, Grube. 

 As regards the first point, I would, from my observations, 

 sum up the generic character as follows (see PL VIII. fig.l) : — 



Cephalic lobes not separated, but only indicated by an 

 emargination on the lower surface. Three inarticulate frontal 

 tentacles, which, by their lively movements and contractions, 

 present throughout their whole length irregular transverse and 

 annular furrows, so that they appear as if twisted. First body- 

 . segment without setigerous feet — but with two tentacular cirri 

 on each side, of the same nature as the cephalic tentacles. On 

 the following segments, on each side, one dorsal cirrus and a 

 uniramous setigerous foot. The composite setge of the foot (fig. 3) 

 have on their short sickle-shaped appendage three uncini — a 

 middle and two lateral ones. Ventral cirri are wanting on all 

 the segments. 



The protrusible, finely chitinized cesophageal tube (fig. 1 a) is 

 surrounded by a muscular sheath, and armed at its anterior ori- 

 fice with a circlet of small pointed teeth, whilst a large median 

 boring-tooth, otherwise so frequently occurring as the armature 

 of the mouth in the Syllidea, is wanting. The oesophageal 

 tube is remarkable for its considerable length, so that only 

 about the anterior half of it follows a straight course, whilst 

 the second half is always folded together in loops. The oeso- 

 phageal tube is followed by the pharynx or glandular stomach 

 (fig. 1 h) common to all SylUdea. This passes, without any 

 special appendages on its lower part, into the intestinal canal, 

 which runs straight backwards, and is lined in its terminal 

 portion with ciliary epithelium. 



In some representatives of Autolytus an alternation of ge- 

 nerations has been observed, of such a nature that from the 

 primary individuals (= nurses — Ammen), by gemmation for 

 the most part, sexual animals are produced and thrown ofi', 

 which contain either male or female reproductive materials, 

 and after swimming about freely for a certain time, reproduce 

 the form of the parent animal by a sexual process. The 

 budded offspring are not only different from the parent ani- 

 mals, but the males and females differ from each other. 



With regard to the second point, I would in the first place 

 once more point out that Krohn was the first who perfectly 

 recognized and declared the genetic connexion between the 



