§22 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 
as to permit some lateral motion. The premaxillary also has no superior 
condyle articulating with the cranium, but the entire length of its supe- 
rior margin is applied in a groove of the ethmoid bone, so as to be 
immovable. Anterior to the premaxillary bones, on the inferior aspect 
of the ? ethmoid, is situated a pair of large, compressed, double-edged 
teeth, whose alveoli are close together. Only oue of these teeth is in 
functional service ata time. In the Hrisichthe penétrans, the superior 
surface of the skull is swollen above the fundus of this alveolus, while 
no such enlargement marks the position of its young companion. 
The compound character of the mandible, and the peculiar mode of 
- articulation of the premaxillary and maxillary bones, entitle this genus 
to recognition as the type of a family distinct from the Saurodontide, 
which may accordingly be called the Hrisichtheide. It is allied to the 
Saurodontide in the mode of implantation of its teeth and in the rela- 
tive extent of the bones of the maxillary arch. 
Three species are represented by the specimens received. They are 
readily distinguished by the forms of the beaks. In the L. nitida, this 
weapon is distinguished by the flat superior surface of its distal half. 
The section in this region is semicircular, a strong angle on each side 
bounding the superior plane, while at the base the section is a transverse 
eval. The flat surface is only finely rugose, while the remainder is 
closely marked with raised ridges, which are- generally parallel, but 
which send off many lateral free or inosculating branchlets. This beak 
is stout, and contracts abruptly at the tip. It is also recurved, and the 
form does not appear to be due to distortion. Length from the inferior 
pair of large basal teeth 0™.155; transverse diameter at base 0.025; 
depth at base 0™.021. 
The second species, which [ call Hrisichthe penetrans, has a snout of 
uniformly oval section at all points. The long diameter of the section 
is transverse. The axis is straight and the form acuminate, the contrac- 
tion being uniform and gradual to acute apex. Thus it follows that a 
beak of greater diameter at the base than one of the Z. nitida has a 
more slender shaft. The teeth of the inferior basal pair are, in the spe- 
cimen described, of large size, and, as in other species, smooth, com- 
pressed, aud with opposite fore and aft cutting edges. The surface of 
the beak is thrown into numerous sharply defined longitudinal ridges, 
which more or less inosculate with each. ‘There is no difference between 
the superior and inferior surfaces in this respect. Length of beak from 
basal teeth 0.150; transverse diameter at base 0".035; vertical diame- 
ter at the same point 0".020; width at middle of the fossee for the pre- 
maxillary bone 0™.060. 
The third species of Hrisichthe is represented by a muzzle of an old 
individual, which has lost a good deal of its apex by attrition. Its sur- 
tace lacks the sculpture of the other species; but whether this smooth- 
ness is due to attrition or not is uncertain. The alveolz for the basilar 
teeth are empty and almost filled up with bone. The form of the muzzle 
