270 Transactions of the Society. 



the present time I can record the following sixteen species of 

 Synchaeta, five of which are here described for the first time :— 



IN BRACKISH WATER. 



8. Synchceta tavina Hood. Greatest size 254 fi ( To ^ in.). 



9. „ littoralis sp. n. Kouss. „ 238 /u, (y£ T in.). 



MARINE. 



10. Synchceta haltica Ehr. Greatest size 523 fi (^ in.). 



11. „ gyrina Hood. 



12. „ triophthalma Laut. 

 [13. „ monopus Plate. 



14. ,, cecilia sp. n. Kouss. 



15. „ vorax sp. n. Kouss. 



16. „ neapolitanas]).ii. Kouss. 



326 fj. ( 7 V in.). 

 265 fj, Q* in.). 



254 /* (to a in-)- 

 142 ^ (Jfo in). 

 340 p Ofe in.). 



I 63 /"(rk" 1 -)- 



Both Prof. Ehrenberg and Mr. Gosse have associated some 

 marine Synchaetae with the luminosity of the sea, for which, how- 

 ever, no evidence has been produced other than the fact that some 

 Synchaetae were found in water which was luminous at the time. 

 Their own experiments showed, moreover, that Synchaeta was not 

 the cause of the luminosity, and the sea-water contained other 

 organisms such as Noctiluca and Peridinia which are known to be 

 luminous. 



The chief characteristic peculiarities of the Synchaetae are their 

 prominent, rounded, ciliated auricles situated on each side of the 

 head, and the more or less cone-shaped body, by means of which 

 they can at once be distinguished from all other Kotifers. Their 

 internal organization also presents peculiarities which are not 

 found in other families. The structure of the large heart-shaped 

 mastax, containing a Y-shaped finely striated muscle, and forcipate 

 jaws, is unique; then also the four large, stiff, styliform frontal 

 setae, which Ehrenberg thought were pincers connected with the 

 jaws, are very characteristic and conspicuous. 



The jaws are of large size, but the parts are so extremely thin 

 and fine that they will hardly sink in the water when dissolved out 

 with potash, and their exact shape is therefore exceptionally diffi- 



