Willemoesia Oroup of Crustacea. 485 



When I read this I began to think that my reverend friend 

 was poking fun at me. Does he really mean to insinuate that 

 he thought I was not acquainted with what every fish-wife 

 knows — the features distinctive between a male and female 

 crustacean ? Reading a little further, I find that the Rev. 

 A. M. Norman had before him two specimens dredged during 

 the 'Porcupine' expedition in 1870 (eight years ago), off 

 the Spanish coast, which, he says, he considers to be " male 

 and female of Polycheles typhlops. Heller ; but the one is, ac- 

 cording to Bate, a member of another genus {Pentacheles) 

 differing from Polycheles in having the last pereiopods chelate, 

 a deeper notch on each side of the front of the carapace, and 

 slight diversity in the lateral and dorsal spiny adornments of 

 the carapace. These are the only two specimens I have seen; 

 my conclusion that their difference is sexual may be wrong. 

 Can Mr. 'QaXo. prove it to be so?"* I have little doubt that 

 I can and will, if he will intrust me with the specimens. 



But why has not the Rev, A. M. Norman determined for 

 himself their sexual relation to each other (he has, it appears, 

 already had them eight years in his possession) ? or is he 

 really in earnest when he says, " Will he let us know how 

 these sexes are distinguished?" Is this the reason why the 

 Rev. A. M. Norman only considers them male and female, 

 and yet criticizes the classification of others, while, in a note, 

 he takes credit for having paired the British Hyperice and 

 Lestrigoni'^ May I ask if he has done this also without obser- 

 vation of the sexual features ? If so, all his arrangements can 

 only be a more or less successful set of guesses. 



As the Willemoesia group consists of animals that have not 

 generally been met with, I would merely remark (and this may 

 be of some assistance to the Rev. A. M. Norman in deter- 

 mining the relation that his two specimens bear to one another) 

 that the organs of generation are generally very conspicuous, 

 and situated as they universally are in macrurous Crustacea ; 

 but there is one feature that accompanies each sex that may 

 be depended upon and be of material assistance in broken or 

 injured specimens. 



The first pair of pleopoda in the female has a tolerably long 

 basal joint, with the terminal branch single and reduced to a 

 feeble condition ; while in the male the basal joint is short, 

 and the terminal one long, stiff, and, shaped somewhat like a 

 marrow-spoon, it lies with the concave surface next the 

 pereion, and is evidently adapted, and I have no doubt is used, 

 for the purpose of supporting the membranous penis during 



* The italics are the Rev.. A. M. Norman's. 



