Insects. 1217 



very diligently many of the other alpine lakes in hopes of finding it, but could not 

 discover the smallest trace of its existence in any of them. The only locality hitherto 

 known is a remote lake on a mountain called Cromaglaun. Following up the new 

 Kenmare road, at the distance of about six miles from Killarney, you arrive at the foot, 

 and unless the proper path be strictly adhered to, you may expect a regular scramble 

 ere you reach the top, on which the lake is situated. That this is a fact I can speak 

 from experience ; for having once had the guardianship of a large party to the summit, 

 in our over-anxiety to reach the scene of action, we left the beaten track in order to 

 steer our course straight up to the lake, the consequence of which, was, we never 

 reached our destination at all ; for after a couple of hours, uninterrupted climbing over 

 rocks, trees, bogs, and streams, finding the attempt utterly hopeless, we were compelled 

 out of respect to our own safety, to descend to the spot from whence we started ! On 

 my first visit I captured about ninety specimens, but the generality of them were so 

 exceedingly minute as to be scarcely larger than an ordinary pin's-head. A few, how- 

 ever, were more bulky, although none so large as a series lately shewn me at Dublin by 

 Mr. Ball, or as Mr. Harvey's specimens, one of which, Mr. Thompson of Belfast 

 describes as being " 5^ lines in length, and 3| in breadth." — T. V. Wollaston ; Jesus 

 College, Cambridge , November 14th, 1845. 



Some account of Gonoplax Rhomboides* — Dr. Milne Edwards, in the second 

 volume of his Natural History of Crustaceans, (p. 62) has given a short description of a 

 species of Gonoplax, of which the specific character is, that it is destitute of spines on 

 the external margin of the shield or carapace, close behind the external angles 

 of the orbits. But of the distinction of this from the only other known species 

 of this genus (G. angulata), a doubt was entertained by Latreille ; who sup- 

 posed that it was nothing more than a variety ; in which opinion he is joined by 

 Mr. Bell, in his beautiful work on Crustaceans, now in the course of publication. 

 And this doubt would appear to be not without reason, if we are guided by the names 

 and references which Dr. Milne Edwards has placed at the bottom of his page. I 

 have no opportunity of consulting the authors there quoted ; but some of the specific 

 names are so strikingly inappropriate to this species as I have seen it, that it becomes 

 clear, that some mystery hangs over the subject ; and we are left to the choice of the 

 following conclusions : — First, that there are other species, yet to be distinguished : 

 Secondly, that the G. rhomboides has been confounded with its congener in one or 

 other of its sexes, or in some stage of its growth : or Thirdly, if they be in reality one 

 species, that a portion of its history is obscure, and that it is more variable in its form, 

 proportions, and armature at different ages beyond early youth, than any others of our 

 crustaceans are known to be. The length of the carapace, including the anterior pro- 

 cess, beneath and on the sides of which the eyestalks are inserted, of the specimen of 

 G. rhomboides under examination, is six lines, the breadth eleven lines ; and this is, 

 I believe, about the size they usually attain. But the distinctions between these crabs, 

 considered as species, will be best expressed by a comparison between them. In doing 

 this, however, I prefer giving a reference to the figure by Pennant (Cancer angulatus, 



* Head before the Natural History Society of Penzance, December 2nd. 



iv 4 m 



