48 



NEW YORK STATE MUSEUM 



Thet 



12] was ver)- slender and covered with a soft skin 

 devoid of scales or of any other markings 

 except those mentioned below. In spite of 

 its delicate structure it is often only moder- 

 ately compressed or distorted. In the region 

 of the posterior dorsal, it may present a some- 

 s' what triangular cross-section, resembling that 

 1 of Cephalaspis in a corresponding region, but 

 g- without any traces of a lateral fold or of fring- 

 t ing processes [/. c, fulcra, or marginal scales 

 "= of other authors]. 



- A few small irregular plates, with the 



= typical sculpture of the buckler, are embedded 

 y- in the skin along the dorsal surface, immc- 

 ;; diately in front of the anterior dorsal, and 

 i numerous minute ones are scattered irregu- 

 i larly over the flanks in the same region. One 

 ~ specimen shows indications of a lateral groove, 

 I and, dorsal to it, a few oblong folds sugges- 

 £ tive of segmentation. 



l The anterior dorsal fin is low and elon- 

 1 gated, the posterior one very high and 

 I rounded. Both fins are often preserved with 

 I wonderful clearness, but show no other detail 

 ^ than a faint striation probably due to the 

 l presence of delicate subdermal rays. 

 I The elongated tail, with its axis slightly 



I curved, terminates in a narrow band. The 

 .- dorsal margin consists of a delicate mem- 

 = Itranc, strengthened by a row of curved rods 

 "S l>ing close together and arranged with great 

 « regularity. The basal ends of the rods are 

 .:: swollen, and one is turned a little to the left, 

 ^ and the adjacent one, to the right of the 

 ■I median line. The rods extend on to the ven- 

 ■S tral margin of the terminal band, into the 

 M ventral lobe. The latter is faintly striated 

 ^ like the dorsal tins. Its anterior ventral 

 "^ margin appears to divide, as though it were 

 continued forward into the lateral folds, 

 although no such folds have been detected m 

 the trunk region. 



There are no indications whatever, either 



