and the Embryology of Autolytus cornutns. 389 



Species allied to Nereis prolifera, owing to this remark- 

 able difference between the males, females, and parent 

 stock, have been placed in no less than four different gen- 

 era. Orsted* is the first who has given a good description 

 of the male of an Autolytus, under the name of Polybostri- 

 chus long-osetosus. Unfortunately, this name cannot stand, 

 as it had been applied before by Brandt, in 1838, to a genus 

 of Acalephs, and must give way to Autolytus which was 

 given by Grube f to the parent stock. From the figure of 

 O. F. Miiller he established a new genus for the male 

 under the name of Diplocercea corniculata.\ Johnston § 

 had given a very good description of the parent stock in 

 the 15th vol. of the " Annals and Magazine." Finally, the 

 female was first seen separated from the parent stock by 

 Johannes Miiller ;|| and he made still another genus, Sac- 

 conereis, for a small worm which he observed in Trieste, 

 belonging to the same cycle. There is also an account 

 of two remarkable worms found by Max Miiller ^ in Hel- 

 goland, and which I am inclined to think are the free 

 young ( (? and 9 ) of the Nereis prolifera of Miiller. This 

 is the more probable, as the observations of Frey and 

 Leuckart were made at the same place, and is confirmed 

 also by the descriptions given by Krohn, apparently agree- 

 ing closely with the drawings given by Miiller (M.), as well 

 as by what I have observed in our own species {Auto- 

 lytus cornutns), where we have males and females differing 

 only slightly from the Sacconereis of M. Miiller; — we find 

 still less difference when we compare the figures of the 



* Orsted (A. S.), Groulands Annulata Dorsibranchiuta, p. 30, PI. V., fig. 62. 

 Kjobenhavn, 1843. 



t Grube. Die Familien der Anneliden, Wieg. Arcliiv, 1850, I., p. 310. 



X Grube. Die Familien der Anneliden, Wieg. Arcliiv, 1850, I., p. 312. 



^ Johnston (Geo.), Syllis prolifera, Ann. and Mag., XV., p. 146, pi. IX., fig. 4. 



II Miiller (Job.), Uebcr den Allgemeinen Plan in der Entwlckeluug der Echiuo- 

 dermen, p. 7. Berlin, 1853. 



1 Miiller (Max), Mull. Archiv, 1855, p. 13. 



