174 Rev. A. M. Norman on Recent Eryontidse. 



material at his command, he had advantages in arriving at a 

 definite opinion which I had not myself enjoyed. The matter, 

 however, was of too great interest to pass by — of so much 

 interest, not to myself only, but to many others, that it seemed 

 the best way to ask Mr. Bate to give us further information 

 upon the points in question. 



I am well aware that the style of my writing was terse. I 

 adopted the form of abrupt questions for brevity's sake ; for I 

 was compelled to compress my observations into the small 

 space of three pages, which had been kindly accorded to me by 

 the Editors of the 'Annals ' at a late period, when the matter 

 for the issue of the next month's number had already been 

 determined on. I regret that it would seem that this brevity 

 savoured to Mr. Spence Bate of discourtesy. 



Whether he is in the right or I am right in the views which 

 we respectively hold is a matter of no moment to myself, if 

 only the discussion of the points in question tends to throw 

 more light upon the subject. 



My first and most important question was, "Are his genera 

 Pentacheles and Willemoesia any thing more than the other 

 sex of Polycheles^ " The first words of the reply are, " Having 

 just given a paper to prove that they are distinct and not one 

 and the same species, I beg to repeat that Pentacheles and 

 Willemoesia are not the other sex of Polycheles, and to refer to 

 my paper for details." I have referred again to his paper, 

 only to find, as before, that there was not one single allusion 

 to sex throughout it. It was this very omission which, on 

 first reading his paper, had led me to the suspicion that Mr. 

 Bate had fallen into the error of regarding certain modifica- 

 tions of structure as of generic value, which really were 

 dependent on and characteristic of the sex of individuals of 

 the same species. The information, however, upon the ques- 

 tion of sex which was wanting in the first paper has, in the 

 second, been supplied. I will now state the grounds on which 

 my own views were arrived at previously to the publication 

 of Mr. Spence Bate's paper. 



1. The known examples with the last pereiopods simple 

 (Polycheles, Bate) were males, while those tvhich had the last 

 pereiopods chelate or subchelate (Pentacheles and Willemoesia, 

 Bate) were females ; thus : — 



A. Males, with last pereiopods simple. 



a, Polycheles typhlops, Heller. The type specimen was a 



male, and has the last pereiopods simple. 



b. Willemoesia crucifera, Suhm, a male ; last pereiopods 



simple. 



