NEW \-ORK STATE Ml'SElTM 



The trun 



k [text fig;. I 2] 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 

 I of Cephalaspis in a corresponding region, but 

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

 .2 ing processes | /. i\, fulcra, or marginal scales 

 e of other authors]. 



£ A few small irregular plates, with the 



g t)pical sculpture of the buckler, are embedded 

 s in the skin alone the dorsal surface, imme- 



cliatel)' in front of tlie anterior dorsal, and 



1 numerous minute ones are scattered irregu- 

 i larly over the Hanks in the same region. One 

 ^ specimen shows indications of a lateral oroove, 

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

 i tive of segmentation. 



\ The anterior dorsal fin is low and elon- 

 'i gated, the posterior one very high and 



1 rounded. Both fins are often preserved with 



2 wonderful clearness, but show no other detail 

 ^ than a faint striation probably due to the 

 'i presence of delicate subdernial ra)'s. 

 s The elongated tail, with its axis slightly 

 5 cur\'ed, terminates in a narrow band. The 

 : dorsal margin consists of a delicate mem- 

 = brane, strengthened by a row of curved rods 

 ^ king 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- 

 f tral margin of the terminal band, into the 

 ^ ventral lobe. The latter is faintly striated 

 " like the dorsal fins. Its anterior ventral 



to 



* 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 



