288 TBANSACTIONS LIVEEPOOL BIOLOGICAL SOCIETY. 



the difficulty of defining species, but it ought to be 

 attempted at the Port Erin Biological Station. It might 

 probably be tried with success on Bathyporeia pilosa, 

 Lindstrom, (the form called B. pelagica, Bate, by Sars), 

 which is common in the harbour and appears to remain 

 in shallow water. If young specimens were kept in small 

 aquaria with sand at the bottom it would be seen what 

 changes they undergo. Very small females with ova were 

 dredged by Mr. I. C. Thompson, in June, in the harbour 

 and, if again taken, would form good subjects for the 

 experiment. 



With regard to the new species described, the first, 

 Nannonyx spinimanus, is not only very distinct from the 

 only other species (N. goesii) but might be thought to 

 require a new genus. It agrees, however, so well with 

 the rather peculiar external characteristics of 'Nannonyx — 

 a genus so distinct that the points on which my species 

 differs might well be omitted and yet leave the definition 

 quite satisfactory — that I have preferred to include it, at 

 the same time pointing out the differences. On the other 

 hand Amphilochus melanops and Photis pollex are so 

 near to other species that were geographical sub-species 

 permissible, I should have preferred to rank them as such. 



I have given the lengths of the largest specimen of each 

 species in my possession for comparison with those of 

 other localities — the length including the uropods but not 

 the antennae. These measurements must, however, be 

 taken for what they are worth as it is impossible to be 

 certain that the specimens have reached their full size. 



The specimens in the list have all been taken by dredg- 

 ing except where otherwise stated. The initials to some 

 of the species mean that the specimen was collected by 

 the gentlemen indicated, as follows : 



W.A.H., Prof. W. A. Herdman, F.E.S. 



