and somewhat variable thickness, Svevaging approximately about two microns. in this 
: y oes igi ADLAt TB Ppa Os 
view the/eapsule infront is/faintly separate from the mandibles, and this-portion-of 
siie—ie nearly ac deep as the head is wide. From it there extends backward ae 
smaller part, 9 microns deep by 9 microns wide, somewhat after the manner of the post=- 
arr 
erior portjon of the pharynx of Bathylaimus, but of course scite as there, @ hollow, 
Cavity. Thies portion now appears a little under one-third as wide. as the base of the 
(44 aga oe ght. et Ss year ) 
head, the posterior limits lying as already described. In this portion of the capsule 
lie whatt may be called the"roots. of the mandiblews The anterior part of the “exo- 
skeleton", or shell, of the mandibles is very distindly differentiated, one to two 
microne thick and refractive. At the base of this portion the labial contour extends : 
almost directly backward, both dorsad and ventrad, the refractiveneas diminishing as — 
the two contour lines finally paas dorsad and ventred respectively and disappear. Aw 
long the very ‘dent of the “valley” of the mandible there is @ narrow refractive ele~ 
ment, 6.5 microns wide; this marking can be followed about half-way to the bottom of 
the main portion of the capsule, where it forks, ite two branches lying at an angle 
of about sixty degrees and pratualiy fading away. 
In the lateral view, a6 well as the dorsal, the oesophageal tissues seem to widen 
out ‘and encompass the posterior, emailer vortion of the pharynx, Bo that at the’ base 
of the larger portion of the head~capsule these tissues occupy three-fifths the dia- 
meter of the bead while a short distance farther back they occupy exiékkie no nore — 
than one-third the diameter. At the base oe kin sharvusk they occupy a little more 
than one-half the diamster. The anterior contour of what has been called the head- 
capsule is aot te be brought intefeous in the leteral view,and hence in this position 
ain all probatility is menlunneted with the surface of the mandible. There ie however 
good evidence that the distal end of the mandible, even back of the anterior borders 
of the head capsule is not rigidly connected with the capsule dorsally end ventrally. 
it. therefore seems beyond question that the mandibles are capable of a conseiderabl¢ 
@ Bitount of lateral, motion. 
DORSAL VIEW. When viewed dorsc-ventrally the mandibles appear always slightly 

