On the Young Stages of a few Annelids. 309 



scarcely necessary to refer to the opinion advanced by Girard,* 

 that the Planarians are naked Gasteropods. 



On the Adult of Loven's Annelid Laeva. 



(Nareda Gir.) ?f 



Although Loven was the first to publish observations on the 

 development of Annelids proper, as early as 18424 wnen ne 

 traced the development of an Annelid, supposed at the time to 

 be the larva of some Nereis-like animal, yet up to the present 

 day, his observations have not been confirmed in spite of the 

 many memoirs we now possess on the metamorphosis of seve- 

 ral families of true Annelids. Milne Edwards, who followed 

 closely upon Loven with a most exhaustive history of the 

 development of Terebella,§ laid the foundation of generaliza- 

 tions on the mode of formation and norm of succession of rings 

 in the young Annelids, which subsequent observations have 

 completely confirmed ; these were somewhat different from 

 what would seem to be logically deduced from the observa- 

 tions of Loven, so that it is of considerable interest to have the 

 observations of the latter repeated, to show that the develop- 

 ment of this larva does not differ very materially from the 

 general mode of evolution observed in other Annelids. 



The large disk of the anterior extremity in Loven's larva was 



* Girard, Ch. Researches upon Nemerteans and Planarians. I. Embryonic 

 Development of Planocera elliptica ; in Jour. Acad. Nat. Sciences. Phil. 1854. 



Girard, Ch. On the Development of Planocera elliptica ; in Proc. Bost. Soc. N. 

 H. III. p. 348. 



•J- Girard, Chas. ; in Synopsis of Marine Invertebrates of Grand Manan, by W. 

 Stimpson ; in Smithson. Cont. 1853. 



\ Loven, S. L. Jakttagelse ofser metamorfos hos en Annelid ; in K. Vet. 

 Akad. Handl. Stockholm. 1840. p. 93. 



Loven, S. L. The same, translated by W. Peters, in Archiv f. Naturg. 1842. 

 I. p. 302 ; also in Ann. d. Scien. Nat. 2me. Ser. 1842. XVIII. p. 288. 



§ Edwards, H. Milne. Observations sur le development des Annelides ; in 

 Ann d. Scien. Nat. 1845. III. p. 145. 



