[ 1G4 ] 



Note on the Early Larvae of Nephthys and G/ycera. 



By 

 H. M. Fuchs, B.A. 



With 10 Text-figures. 



The larva of jVcphthi/s was originally described by Claparede and 

 Mecznikow (2) in 1868, from specimens obtained from the Plankton at 

 Naples. Since then it has been figured by Fewkes (3), Hacker (5), and 

 Gravely (4). The larva of Glyccm is, as far as I am aware, hitherto 

 undescribed. 



The larvie described below were reared in the laboratory at 

 Plymouth, at the suggestion of Dr. Cresswell Shearer, from artificially 

 fertilized eggs. Both Nephthys Homhergi* and Glycera convolnta can 

 be obtained from the sand in Jennycliff Bay at low water. Nei^hthys 

 occurs more commonly than Glycera. but large specimens are not fre- 

 quent. On the other hand, very young specimens are completely 

 absent. It is at present altogether unknown what becomes of the 

 young of these worms from the time when they sink down from the 

 Plankton until they grow to about an inch in length. From June to 

 August most of the larger individuals contain ripe sperm and ova, 

 which are frequently discharged in captivity, within a day or two from 

 the date of capture. It was found unnecessary, however, to wait until 

 the generative products were shed naturally. The method of procedure 

 was as follows : The worms were slit up with a pair of scissors and 

 placed in " outside " sea-water in sterilized finger-bowls, the males 

 being kept apart from the females. As soon as the sexual products 

 emerged from the body cavity the worm was removed, several being 

 treated in this manner to ensure the presence of ripe eggs. A few 

 drops of liquid from the suspension of sperm was then added to the 

 bowl of eggs and the latter stirred and allowed to settle. Wilson (9) 

 has stated for Nereis and Treadwell (8) for Podarhe that if the eggs are 

 cut out of the body of the female, segmentation is irregular. This is 

 not the case with Nejjhthys and Glycera. As soon as the larvae swam to 

 the surface they were pipetted off and placed in jars of filtered sea-water. 



All attempts to feed the larvie failed, and in consequence, although 

 they could be kept alive for three weeks or a month, after about 



* It is just possible that a few small specimens of -V. caeca were included with the 

 N. Homlergi. 



