ON PLATYSOMUS FOESTERI. 413 



This is a very distinct species, and is at once distinguished 

 from P. striatus by its small size and the much greater delicacy 

 of its parts : the scales of striatus are wide, thick, and coarse in 

 comparison with those of P. rotundas, in which they are thinner 

 and much narrower than in any other species with which we are 

 acquainted ; and, moreover, the striae in P. striatus are much 

 more numerous and more oblique. The same features equally 

 distinguish our new species from P. gibbosus, which is apparently 

 a close ally of P. striatus. On account of its small size, it might 

 possibly be confounded with P. parvulus : but the scales of the 

 latter are twice the width of those of the former, and the striae 

 are much more numerous ; the head-bones, too, are tuberculated, 

 while in P. rotundus they are, as we have already pointed out, 

 striated ; the teeth of P. parvulus are likewise considerably 

 larger. 



Of the inedited species P. declivis, Agassiz, we know very little, 

 but understand that the scale is similar to that of P. striatus : 

 the name, too, so far as it is descriptive, is certainly not spe- 

 cially applicable to P. rotundus. 



Platysomus Foesteri, n. sp. 



We have in our possession considerable portions of three 

 specimens of another species of Platysomus that appears to be 

 undescribed; they were all obtained at Newsham. Unfortu- 

 nately, the general contour cannot be traced in any of them ; the 

 fins are not present ; and though many of the cranial bones are 

 well preserved, they are all scattered. We shall therefore have 

 to rely mainly on the scales for specific characters. The scales 

 (PL XV., fig. 3) however, are sufficiently marked to distinguish 

 the species from all its congeners, and are in good condition. 

 They are large, measuring nine-tenths of an inch in length, 

 including the peg, and two-tenths of an inch wide ; they are 

 consequently long and comparatively narrow ; the form is rhom- 

 boidal ; the peg is long, and tapers gradually to a fine point ; 

 the smooth anterior margin of the scale is rather wide, the rest 

 of the surface being covered with close-set, raised, longitudinal 

 stria?, which are somewhat undulated and slightly diagonal, 



