A POLYNOID WITH BUANCHI^. 441 



species^ of this sub-family were knowiij all about equally dis- 

 tant from one another, it was quite enough to have only one 

 genus for them all, as Grube proposed. But the greater the 

 number of species made known the less likely are they to 

 remain equally distant from one another, and they then fall 

 naturally into groups, only to be reunited when all the inter- 

 mediate forms are known. In my opinion the sub- family of 

 the Acoetidse falls now, in the present state of our knowledge, 

 or rather of our ignorance, into three groups, which we may 

 call genera. One of these, the genus Eupolyodontes, I 

 have already defined. The other stalk-eyed forms (Polyo- 

 dontes maxillosus and Blainvillei; Acoetes Pleeij 

 Eupompe Grubei, australiensis, and indicaj Pan- 

 thalis Oerstedi, gracilis, melauotus, and [in part] bi- 

 color) I would propose to put together in the genus Polyo- 

 dontes, defining this genus then in its widest sense as follows: 



2. Genus Polyodontes. 



Acoetidse with peduncles of eyes arising from the front of 

 the prostomiura, and meeting, or nearly meeting, one another 

 in the middle line in front ; median prostomial tentacle well 

 developed, paired ones present in all except P. (E.) indica 

 and P. (P.) melanotus, and arising from the ventral surface 

 of the prostomium at the base of the eye-stalks ; palps large 

 and well developed, arising close behind the paired prostomial 

 tentacles ; papillae sometimes present on the parapodia, but 

 not developed to any great extent (represented in P. (A.) 

 Pleei,, P. (E.) australiensis, P. (E.) Grubei [on elytra- 

 bearing feet only], and P. (P.) bicolor?^). Parapodia of 

 buccal segment sometimes chsetiferous (at least in P. maxil- 

 losus, P. (A.) Pleei, P. (E.) Grubei, and P. (P.) Oerstedi, 

 but not in P. (E.) indica, P. (E.) australiensis, or P. (P.)bi- 

 color; in the other species the fact is not mentioned either way). 



I have the less hesitation in placing these species of different 



' At present, in this sub-family, it is easy to speak of these " different 

 forms " as " species." 



' If I understand Grube's description aright they would be here on the 

 ventral surface of the parapodia, and not on the dorsal. 



