On the Young Stages of a few Annelids. 303 



XXXIV. — On the Young /Stages of a few Annelids. 



By Alexander Agassiz. 

 Read June 25, 1866. 



The study of immature animals has become so important 

 that, before proceeding to my subject, it may- be of some in- 

 terest to those engaged in investigating marine animals, to 

 know how the young may be collected. Johannes Miiller was 

 the first who successfully employed surface dredging with a 

 tine gauze hand-net ; he has been followed with eminent suc- 

 cess by many of his pupils, and now scooping the surface of' 

 the sea in search of diminutive animals, scarcely to be recog- 

 nised with the naked eye, is one of the most profitable sources 

 of supply for recent investigators at the sea-shore. Baur* has 

 introduced fishing with the gauze net by sinking it to any de- 

 sired depth, and this promises to be a fruitful mode of finding 

 what cannot be reached with a hand net. Meyer and 

 Mobius,f in their investigations of the Fauna of the Bay of 

 Kiel, have even attempted, with remarkable good fortune, to 

 pump up from the vicinity of the bottom any animals there 

 abounding. 



As a rule, the habits of the young marine animals are so 

 utterly different from those of the adult, that we cannot expect 

 to find them together, and must not search for the young in 

 the retreats where lie concealed the adult Crustacea, in the mud- 

 flats or sandy beaches where are buried Annelids and Mollusca, 

 along the rocky shores where so many Gasteropods abound, or 

 under sea-weeds and stones, the hiding-places of both Annelids 

 and Mollusks, as well as Crustacea. We must not look in 



* Baue, A. Beitrage zur Naturgeschichte der Synapta digitata ; in Ver- 

 handl. der K. L. C. D. Akad. 1864. 



f Meter, H. A. u. Mobius K. Fauna der Kieler Bucht. 

 JUNE, 1866. 23 Ann. Lyc. Nat. Hist. Vol. VIII. 



