Dr. il. GreefF on Autolytus prolifer. 175 



completely omitted both in the description and in the numerous 

 figures. Clapar^de, who also notices this defect, in his valu- 

 able work on Annelides published in 1864*, has reestablished 

 the genus Autolytus as previously indicated by Krohn, and 

 has also enriched our knowledge by three fine new species. 

 Ehlersf, on the contrary, in his work on the Polychseta, has 

 again treated our genus very unkindly, forming a new genus, 

 Procercea {picta) of a worm which appears to be undoubtedly 

 an Autolytus. That the dorsal cirri on the third body-segment 

 are rather longer than on the following segments (which, 

 moreover, occurs also in other representatives of Autolytus — 

 for example, in A. scapularis^ Clap.) cannot possibly suffice 

 by itself for the establishment of a new genus ; and yet this 

 appears to be the only differentiating character, as in other 

 respects, according to the excellent and careful description and 

 figure, Procercea picta in all its essential characters is a true 

 Autolytus. Nor must Ehlers's worm be separated from Auto- 

 lytus merely because Ehlers observed no alternation of genera- 

 tions in it. Without taking into consideration that the state- 

 ments as to the sexual conditions in Procercea are imperfect, 

 even the ascertained absence of alternation of generations, 

 such as Clapar^deJ quite correctly establishes for his A. sca- 

 pulariSj would by no means of itself justify the establishment 

 of a new genus. I therefore think that I may propose to 

 change Procercea picta provisionally into Autolytus ptictus. 



Under the generic name Polyhostrichus, QErsted, already 

 referred to, and the connexion of which with Autolytus has 

 been described by Agassiz, Keferstein§ has likewise furnished 

 valuable observations on the male bud of Autolytus j the iden- 

 tity of which with Max Muller's Sacconereis helgolandica he 

 endeavom'S to demonstrate. It is remarkable, however, that 

 in neither of his memoirs does he say a single syllable of the 

 genetic connexion of Sacconereis and Polyhostrichus with Auto- 

 lytus^ so definitely expressed by Agassiz and Krohn, but treats 

 his Polyhostrichus as a perfectly independent genus. 



My own communications are founded upon observations made 

 last year in Heligoland, and partly also during a subsequent 

 residence on the coast of the Channel (chiefly at Ostend) . Their 

 principal object is the discussion of three important points in 

 the natural history of Autolytus^ in the face of the still greatly 

 varying statements, as above indicated, namely : — in the first 



* Glanures zootomiques paniii les Annelides, p. 102, pi. 7. 

 t Die Borstenwiirmer, (Leipzig, 1864) p, 263. 

 X Loc. cit. p. 109. 



§ Zeitsclir. fiir wiss. Zool, Bel. xii. p. 11.3, pi. 11. figs. 1-6, and p. 464, 

 pi. 42. figs. 5-11. 



13* 



