2i0 Hoi.T & BeaUiMONT — Siirrc// of Fishing-r/roitnds, W. Coast r>f Irrland, 1890—91. 



The above characters, if constantly found associated in individuals, Avould 

 certainly enable us to name specimens either M. flcxuosa or M. neglecta, leaving to 

 higlier autliorities the task of deciding whether or no the somewliat minute differ- 

 ences enumerated were really of specific moment. However, in the Irish examples, 

 the characters prove to be mixed in individuals or compromised by the occurrence 

 of intermediate conditions. 



The number of joints in the tarsus lias the appearance, on jDaper, of a well- 

 defined character, and it may be easy for an expert to count the joints in all 

 examples. We ourselves have often experienced the greatest difiiculty in this 

 matter, since the proximal articulation is often so faintly indicated, even under a 

 moderately high power, that it is impossible to decide whether it is entitled to 

 rank. Moreover, the number of joints often varies in the anterior legs of the 

 same individual, as may be seen by the following figures : — 



Articulations of tarsus of legs ^ from in front backwards. '\ 



Specimen. Specimen. 



A. 6, 6, 6, 5, 5, 4. I. 5, 5, 6, 5, 5, 4. 



B. 5, 5, 6, 5, 5, 4. t "^ .- . n^ ^-5 (") • 



C. 5, 6, 6, 6, 5, -. 6 4 



■"* X. Au anterior leg, 4. 



D. 5-6 (?), X, -, 6, 6, 5. 5 5 

 6 L. -, -, X, X, 5, 4. 



o 



E. 5, —^^' 6, 5-6(?), 5,4-5 (??). 4 



•5-6 (?), 



■ 6 M. 4-5(?), 5, 5, 5, 5 (?), ^. 



F. 5, 5-6(??), 5-6(?), 5, 5, 4. ^^ ^^-1 



G. 5, 6 (?), 6 (?), 5, 5 (?), 4. N. x, 5, a leg anterior to last 4. 



If the presence of a sixth articulation is a crucial point of distinction, A to J 

 must be M. flcxuosa, while L to N are 31. neglecta. The specimens are enumer- 

 ated in the order of size, A to K measui-ing 24 to 15 mm. (including antennal 

 scales and telson) ; L to M 13 to 12 mm. In the case of ScJiistomysis ornata, 

 Norman, in deciding P. Kervillei to be a synonym of the first-named species, 

 attaches no importance to the extra joint of the tarsus present, but apparently not 

 invariably, in large specimens. We cannot see why the character should have 

 greater value in Macromysis, in which, indeed, we have given some little 

 evidence that the number of joints may increase with the age or size of the 

 specimen ; although since M and N are fully developed males, it be not correlated 

 to sexual maturity. 



f Two figures separated by a hyphen and followed by a note of interrogation indicate that the exis- 

 tence of the larger number of articulations (six in 5-6 ?) is doubtful. The doubt is greater where two 

 notes of interrogation are employed. A single figure followed by a note of interrogation means that the 

 proximal articulation was observed, but only iudistinctly formed. Figures shown as fractions (%\ refer 

 to a pair of legs. 



