I 



STAEKS: THE CHARACTERS OF ATELAXIA. 19 



extending forward to the parietal ; the lower pharyngeals rod-like and parallel 

 with the branchial arches (or absent ?) ; the dorsal composed of soft inarticulate 

 spines ; a pelvic girdle present. 



In the above comparisons I have used the beautifully illustrated and detailed 

 report of T. Jeffery Parker on the skeleton of Regalecus argenteus ^ (Trans. Zool. 

 Soc, 1886, vol. 12, p. 5-34, pi. 2-6). 



The Osteology of Stylephorus. 



The posterior part of the cranium is normal in position and number of the ele- 

 ments, except that the opisthotic and basisphenoid are absent.'^ 



The pterotic is a rounded bone, normal in position and size, but without a 

 process. The epiotic process is reduced to a mere tubercle of bone to which 

 the upper shoulder girdle element is attached. 



The alisphenoids are well separated from each other by the wide anterior open- 

 ing to the brain case. 



The myodome is well developed, but broad and short and not opening to the 

 exterior at the posterior end of the parasphenoid. 



Each exoccipital shares equally with the basioccipital the support of the verte- 

 bral column. 



The ethmoid is a thin vertical plate but little ossified projecting forward from 

 the frontals. Along the posterior edge of the ethmoid the poorly ossified pre- 

 frontals stand outward at an angle on each side. 



The vomer is a very small bone situated behind the ethmoid and prefrontals on 

 a slightly downward projecting portion of the parasphenoid. In the majority of 

 bony fishes the vomer is anterior to the ethmoid and the prefrontals, and is 

 suturally connected to them at its upper posterior edges. 



From the upper surface of the lateral wings of the parasphenoid, just behind 

 the vomer a long slender process springs and runs forward far beyond the vomer. 

 It is thin in the middle and somewhat thickened and rod-like at each edge. To 

 the upper surface of this the thin ethmoidal plate is attached, and the rod-like 

 edges pass under the lower ends of the prefrontals, though the attachment to the 

 prefrontals is not close. The relationship of the rod-like portions of this process 

 to the prefrontals suggests that they be the palatines, though the attachment of 

 the ethmoid to the upper surface of the process is against this supposition, unless 



1 Mr. Parker's paper illustrates the value of descriptions and drawings in detail 

 of every skeleton reported upon even when a detailed description may be irrele- 

 vant to the problem in hand. 



Descriptions and illustrations of skeletons of rare forms are valuable though the 

 author may have no problem in connection with them. 



2 The importance of these elements is apparently not great ; the presence of 

 the former depending in some degree upon a lower limb to the posttemporal, or at 

 least a well developed ligament representing a lower limb. The absence or pres- 

 ence of an opisthotic or basisphenoid seems to be little more than generic in 

 value. 



