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at its infero-lateral corner, while its more medial half is to all appearance 
ill-supported. On its anterior aspect, however, this latter part abuts against 
the rod-like projection already mentioned as arising from the internal 
aspect of the keel of the buccal frame. Springing from a point that 
corresponds to the anterior angle of the articular foramen for the second 
maxilla, i.e. some little distance in front of the alar plate, and rigidly 
connected to the keel, this calcareous rod runs backwards and upwards 
at an angle of about 30 degrees with the cephalosomic floor to unite, 
apparently by a chitinous joint, with the alar plate just at the indenta- 
tion between the superior and the inferior medial pterygoid processes. 
Its (mathematical) projection upon the cephalosomic floor would coincide 
with the chitinous band separating the articular foramina for the two 
maxillae. This rod, which we must reckon as a constituent part of the 
ventral endophragmal skeleton, besides acting as a very efficient strut to 
the alar plate, no doubt gives origin to some of the muscles which move 
the maxillae. 
The fourth attachment of the alar plate to surrounding parts takes 
place by means of a very long process which springs from the superior 
medial pterygoid process — see fig. 19. Lloyd has described it under the 
name of the “ anterior portion of the sternal ala ” ; we shall call it the 
pharyngeal process. It has a broad base, which is firmly fused to the 
pterygoid process along the whole width of the latter, and is situated 
at a higher level than the attachment of the rod-like strut described in 
last paragraph, which it consequently hides from view. The basal portion 
is a triangular lamina which lies in a horizontal plane, and whose apex is 
produced into a long process like a sabre with back and edge arranged 
vertically. At its commencement the sabre is straight, horizontal, and 
calcareous ; its distal two-thirds, chitinous and flexible, sweeps upwards 
in a curve to gain attachment by a clubbed extremity to the internal 
surface of the cephalon a little above the fossa for the antennule. The 
pharyngeal process does not confer any special rigidity upon the alar 
plate ; on the contrary, it derives its own fixity from its firm attach- 
ment to the plate. According to Lloyd, it gives origin to the muscles 
which move the foregut. The triangular basal portions of the two 
pharyngeal processes, diverging like a V, form a platform upon which 
the foregut rests. The two sabre-like extremities intervene as thin slips 
between the pharynx and foregut on the one hand and the adductor 
calcification of the mandible (see p. 291) on the other. 
It may here be mentioned that the alar plate gives direct attachment 
to the first or basal segment of the first maxilla. Previous workers must 
