98 NEW YORK STATE MUSEUM 



place. This fact as well as the presence of other characters hitherto 

 unknown have suggested this note, the material having been kindly- 

 presented to the New York State Museum by Mr Burling. 



The shape of most of the individuals in both the American and 

 British graptolite shales being more or less modified by pressure, it 

 is somewhat hazardous to base specific differences on the outline of 

 the carapace. The British authors, however, have separated a very 

 narrow form as C. m a r r i i f roin the broader w r i g h t i i . 

 Of the three species distinguished by Gurley among the American 

 forms, C. w r i g h t i i may be rejected on the ground that the 

 author based this identification on telsons and a misconception of the 

 structure ; his C. oblongus, a Point Levis form, and said to 

 be distinguished from the others by its " regularly oblong shape " is 

 too imperfectly known to concern us here. His C. c u r v i - 

 1 a t u s , however, from the Beekmantown graptolite shale of Sum- 

 mit, Nevada, as based on his first figure (see text figure 38) appears 

 to comprise the form before us from the Alaska-Yukon boundary. 

 At any rate, the latter is not sufficiently different either in age or out- 

 line to warrant distinction in this place. 



One of the bivalved carapaces (see text figure 46), 22 mm long, 

 though not perfect in front, retains a short, rapidly tapering abdomen 

 6.5 mini long in which five segments can be distinguished, beyond the 

 posterior extremity of the carapace, not counting the last segment 

 which may represent the telson (the specimen is not complete at 

 this end either). Another detached abdomen (see text figure 49) 

 exhibits five segments and a fragment of a sixth, besides the telson 

 spine, so that it may be said with reasonable security that the 

 abdomen of Caryocaris consisted of six or more segments. The 

 caudal appendages (see text figure 50) consist of a broadly acute 

 style (telson) that is flanked by two somewhat leaflike expanded or 

 lanceolate stylets or cercopods. The inner edge of these were seen 

 in the Nevada material (see text figure 44) to be provided with 

 fine setae. 



The carapace was considered by Salter as being broader 

 posteriorly, Jones and Woodward (op. cit., p. 90) preferred, how- 

 ever, " to regard the broader and prow-shaped end as the front." 

 Our material fully supports their contention. 



The posterior margin appears often provided with a fine ciliated 

 fringe. Jones and Woodward observed this, but owing to the 

 " plaiting " or imperfect cleavage of the compressed flagstone 

 attributed this feature to the incidents of preservation, stating that 

 owing to this cleavage, " occasionally, when they [the valves] lie 



