154 Carc'inological Fauna of India. 



The four ambulatory legs have the form of swimming-paddles, 

 the two terminal joints being broadened and compressed — in the first 

 and last pairs of legs enormously so. 



The abdomen in the adult male consists of 5 segments, owing to 

 the intimate fusion of the 3rd, 4th and 5th terga : in the female and 

 young male all 7 terga are distinctly separate. In both sexes the first 

 tero-um is almost entirely concealed beneath the carapace. 



In the adult male the third tergum is very strongly carinate trans- 

 versely, and the second moderately so. In the female and young male 

 both the second and third terga are strongly carinate, and if there is any 

 inequality it is the second that is most prominent. 



Owing partly to their great similarity, and partly to the insufficient descriptions 

 of earlier authors, the discrimination of the species of Matuta has always been 

 a matter of difficulty.* 



The first species described and figured is the Cancer lunaris of Rumph (Am- 

 boinsche Rariteitkamer p. 11, pi. vii., fig. S. 1705), a species characterized by the 

 possession of an entire (i.e., not bifid) rostrum and of a very sharply defined tuber- 

 cle near the middle of either posterior border. 



This species must, I believe, be (1) the species called M. banhsii by Leach, 

 Miers, and subsequent authors, (2) the M. picta of Hess and Miers, (3) the M. dis- 

 tinguenda of Hoffmann, and (4) the M. obtusifrons of Miers. I think also that the M. 

 granulosa of Miers and de Man is only a slightly abnormal form of Rumph's species. 



Rumph's name having unfortunately been accepted for a quite different post- 

 Linnaean species, cannot now be used ; and Rumph's species must therefore bear the 

 earliest applicable post-Linnasan name — namely M. banhsii, Leach. 



M. banhsii according to Leach can be recognized by a very strong tubercle 

 behind the lateral spine. 



The second known species of Matuta is the Cancer americanus of Seba 

 (Thesaurus III. 52, pi. xx., figs. 10, 11. 1758), of which it is impossible to say more 

 than that it roughly represents the form of the genus Matuta. 



Herbst (Krabben, etc., 1790-1799) described and figured two species of Matuta. 

 One (Krabben, I. ii. 140, pi. vi. fig. 44), he called C. lunaris, and this he says is 

 Rumph's species, quoting Rumph's Latin and vernacular names : the other (I. ii. 

 143) he called C. victor of Fabricius. Subsequently, however (III. ii. 43) he re- 

 named C. victor C. lunaris, figured it on pi. xlviii. fig. 6, and stated that his C. victor 

 and C. lunaris are the same species. 



Herbst's two figures — pi. vi. fig. 44 and pi. xlviii. fig. 6 — are so different, 

 however, that doubts must still remain as to whether they both really do refer to 

 the same species, and it does not seem to me that Hilgendorf's observations, to be 

 presently referred to, clear these doubts up. I believe myself that Herbst's plate 

 vi. fig. 44 might still be regarded, as Herbst at first seems to have regarded it, as 

 representing Rumph's Cancer lunaris. 



Fabricius who (Entomol. Syst., Suppl. p. 369, 1798) instituted the gemis Matuta, 

 included in it two species — M. victor and M. planipes. We know, from Hilgendorf's 

 paper to be presently considered, to what species of modern authors these refer. 



* Unfortunately I have not been able to see Latreille's article on the genus 

 Matuta in the Encyclopedic Methodique, Vol. X. 

 159 



