119 



legs are completely preserved, while in the rest these legs are partly or entirely broken off: 

 this is a great pity in connection with the remarkable fact that the measurements of 

 the three posterior legs vary rather considerably. Stanley Kemp has first 

 observed this variability, for in his valuable work on the Decapoda Natantia of the coasts of 

 Ireland he writes, p. 95: "The exact length of these limbs is by no means constant; the female 

 specimen mentioned above ]5robably represents an extreme case". When we look at the Table 

 of Measurements, in which the exact length of the joints of one or more posterior legs of 

 21 specimens has been recorded, the following observations can be made. The carpus appears 

 nearly eciually long in the 3"', 4"^ and 5"^ pair; it measures in the 3'^ pair about three-fifths, 

 in the 4"^ two-thirds and in the 5'i> about four-fifths of the respective merus and ischium combined. 

 In the adult male from .Stat. 173 the propodus of the 3^<^ legs is little shorter than the 

 carpus, but almost in all the other specimens it is considerably shorter, measuring only 

 one-half to two-thirds the length of the carpus: in the young female from Stat. 262 and 

 in a young male from Stat. 316 the propodus appears a little longer than the carpus! In 

 the figure of Pies, iiiartia in A. Milne-Edwards' "Recueil" the three posterior legs are no 

 doubt incorrectly figured, because the propodus of the 5"' leg appears shorter than that of the 

 3'^'^, which certainly never takes place. In the figure of this species, published by Senna (1. c), 

 the carpus of the 3"' pair appears slightly shorter than the propodus, like in the adult male 

 from Stat. 173, in Kemp's figure (I.e. PI. XII) and in the figure oi Pies, semilaevis in the 

 Report on the Challenger Macrura (PI. CXIII, fig. 93), both joints show about the same lengtq- 

 In the adult male from Stat. 173 the propodus of the 4"' pair is nearly one and a half as long 

 as the carpus, almost as in Bate's figure, and in the young male, long 96 mm., from .Stat. 

 316 even more than twice as long as the carpus, but in the male N'-' 6 from .Stat. 12 the 

 propodus is hardly one-third longer than the carpus and in the other specimens the carpus 

 is just as long or even a little longer than the propodus. In the figures of Senna and 

 Kemp the propodus of the 4"' pair appears almost twice as long as the carpus. The 5''' legs 

 of the young male from Stat. 3 1 6 resemble the figures of the typical species in the papers of 

 Senna and Kemp, the propodus being nearly 2Y2-times as long as the carpus; in Bate's figure 

 of seniilacvis the propodus appears twice as long as the carpus, such a specimen is the male 

 N" 6 from Stat. 12. In the few other specimens in which these legs were still preserved, the 

 propodus is only one and a half as long as the carpus or little more, in the young specimen 

 N" 20 from Stat. 3 1 2 the propodus is even only one-third longer than the carpus. These 

 variations in the relative length ot the joints of these legs do not seem to depend u|jon the 

 age of the specimens. The specimens N" 6 and N" 21, respectiveh- only 97 mm. and 96 mm. 

 long, nearly agree with Kemp's figure of a full-j^rown, ovigerous female, while this is not the 

 case with the other specimens, that are longer and thus much older, rnfortunalely no mea- 

 surements at all of the three posterior legs are given by the authors which have described or 

 studied this species. New investigations and measurements both of indopacific and east atlantic 

 or mediterranean specimens are therefore necessary in order to decide the question, whether 

 constant differences exist or not between the typical species from the Ea.st Atlantic and the 

 variety scviilaevis from the indopacific seas, as regards the measurements of these legs. 



