78 ISCHNOCHITON. 



Var. PUNCTATUS Whiteaves. 



Sculpture as in reteporosus, but the riblets of end valves and 

 lateral areas are more delicate, subobsolete; and the network of the 

 central areas is shallower. Color pale cream, nearly white, with a 

 spot of orange-brown on the ridge of valves ii to viii, and a few irre- 

 gular spots of reddish on the white girdle. 



Length about 8 mill. ; divergence 100 (specimen somewhat 

 curled). 



Discovery Passage, at Duncan Bay, Vancouver Island, 10-20 fma. 

 (Dawson). 



Leptochilon punctatus WHITEAVE^, Trans. Roy. Soc. Canada, iv, 

 Sect, iv, p, 125, figs. 1886. 



This very pretty form may for the present be retained distinct as 

 a color-variety, but intermediate specimens must be expected. The 

 occasional, rather spaced growth lines are more marked than in the 

 typical reteporosus. I am indebted to J. F. Whiteaves F. G. S. for 

 an opportunity of examining the type specimen (at present unique), 

 which is the property of the Canada Geological Survey. 



I. SERRATUS Cpr. PL 16, figs. 42, 43, 44, 45, 46. 



The original description is given on p. 122, vol. XIV. 



The shell is moderately elevated, bluntly angled along the ridge, 

 side-slopes nearly straight. Color light buff, with small olive spots 

 sparsely scattered along the dorsal ridge and the posterior margins 

 of each valve, and having some irregular orange maculae on the 

 pleura of some valves. 



The intermediate valves are very minutely and densely granulated 

 throughout ; lateral areas raised, composed of 2-3 (on one side of 

 valve ii, 5) wide rounded ribs ; the hind border of each valve very 

 unevenly toothed (fig. 43). Central areas having about 12 longitu- 

 dinal low riblet* on each side, crossed by several transverse riblets, pro- 

 ducing a shallow and not very distinct appearance of grating. The 

 head ninl toil valves each have about 20 low ribs, like those of the 

 lateral areas. Tail valve with subcentral mucro (figs. 42, 44.) 



Girdle faintly tessellated with delicate green and whitish, clothed 

 with solid, somewhat flattened scales, averaging one-sixth of a mill, 

 in width, and when unworn they are very delicately striated (fig. 45, 

 x 150 diameters). The individual scales are dull bluish, fading at 

 the edge. 



Length 8J, breadth 5* mill. 



Cape St. Lucas. 



