720 MR. W. F. LANCHESTER ON CRUSTACEANS [June IP, 



Cape Kachado, where Mr. Bedford spent some time after my 

 return home, he obtained several examples of Matnta, a genus of 

 which, out of the three species in the collection, only one conies 

 from Singapore. 



As regards the systematic part, I have described as new 5 

 varieties aud 7 species, and 2 of the species have had to be referred 

 to new genera : one, a Leucosiid of the Oreqphorus type, which is 

 interesting because of the great lateral expansion of its carapace ; 

 the other, a small form with a very general resemblance to an 

 Actcea, especially in the front and orbits, but with well-marked 

 palatal ridges and other differences. As regards the common 

 genus Thalamita, of which there are 3 species, I had hoped to be 

 able to set at rest the question of the value of their specific 

 characters, but was unfortunately unable to obtain sufficient 

 specimens for comparison ; but from what I have myself seen, and 

 taking Kossrnanirs (Zoolog. Ergebn. p. 48), and other scattered, 

 evidence into consideration, I think it strongly probable that some 

 at least of the species should be united — as, for example, the three 

 in the collection, T. crenata, T. spin in tana, and T. dance. Dr. de 

 Man (Mergui Crust, p. 78) has laid some stress on the form of 

 the lobes of the internal angle of the eye ; but these are certainly 

 variable in the specimens I have examined. 



I have taken measurements of the breadth and length of the 

 carapace of nearly all the individual examples of each species, and, 

 but for the lack of space, would have given the length of the 

 rostrum, lateral margins, &c, in order to make the list more 

 complete. It is, of course, very difficult to find any constant lines 

 of measurement, owing to the variability, in the same species, of 

 the form of the carapace ; spines, whether rostral or lateral, are 

 notoriously variable, and there is no necessary constancy in the 

 straightness, or amount of convexity or concavity, of the frontal 

 and posterior marginal lines. Under these circumstances, I have 

 taken the following bases of measurement : — In the Oxyrhyncha, 

 Cvclometopa, and Oxystomata, the length from the middle of the 

 posterior margin to the middle of a line drawn from the one base 

 to the other of the praeocular or internal supraocular (as the case 

 may be) spines : such a line approximately defines the base of the 

 rostrum. I have never found the prse- or supraocular spine so 

 ill-developed that this line cannot be traced. The breadth, in 

 these groups, has been taken from the anterior base of the last 

 lateral (Cyclometopa) or epibranchial (Oxyrhyncha) spine, or from 

 the epibranchial angles. In the Catometopa, however, I have 

 found myself obliged to include the rostrum in the measurement 

 of length, and to take the breadth from the point of one external 

 ocular spine to that of the other. None of these measurements, 

 however, can be considered as other than approximate ; I give 

 them, as I have taken them, for what they are worth. They 

 certainly do show a variability in proportions, which, though 

 slight in a great many species, is in others rather striking. 



As regards the references that are given, under each species, I 



