NOTES ON THE NAIDIFORM OLIGOOH^TA. 345 



One of the most interesting features in the anatomy of this 

 worm is the condition of the setae in the cephalized segments. 

 The first pair of ventral seta bundles, viz. those belonging to 

 segment ii, are larger than those in the two following segments. 

 Those in segment iv are very small, and seldom contain more 

 than two setse — indeed, they are frequently altogether absent ; 

 but I have always found them in a newly budded head, so 

 that when they are absent it is doubtless because they have 

 dropped out. I have unfortunately no other notes with regard 

 to the budding. 



Ophidonais, Gervais (see woodcut). 



Four cephalized segments in addition to the peristomial seg- 

 ment are well marked in the fully grown head. 



There is no prostomial tentacle. 



There are no capillary setae. 



There are no branchial processes. 



Eyes are present in the only known species. 



The only other known genus of Naids in which capillary setae 

 are absent is Paranais. 



1. O. serpentina. 

 This species is well known in England ; all the dorsal setae 

 are spear-shaped and straight. 



Slavina, Vejdovsky (see woodcut). 

 Four cephalic segments in addition to the peristomial segment 

 are well marked in the fully grown head. 

 There is no prostomial tentacle. 

 The dorsal setae are capillary. 

 There is a girdle of papillae in the middle of each segment. 



1. S. appendiculata, Vejdovsky. 

 1 received a few specimens of a species of Slavina from 

 Mr. Bolton, but have no notes which enable me to offer an 

 opinion as to the identity or otherwise of the English species 

 with S. appendiculata, Vejdovsky. 



According to Bousfiekr the English species is identical with 

 the Nais lurida of Timm, and he calls it S. lurida, and 

 ' ' Journ. Linn. Soc. Zoology/ vol. xix, 1880, p. 264. 



