340 S. I. Smith. — Early Stages of Hlppa talpoida. 



The second i)air of maxillie offer no marked peculiarity and are 

 essentially of the same form as in the megalops-stage (Plate XL VII, 

 fig. 3). The two principal lobes of the protognath are very similar 

 in form and structure to, lie directly over, and doubtless act in direct 

 conjunction with, the two corresponding lobes of the first maxilla. 



Remipes. — The general structure and arrangement of the parts 

 of the mandibles and both pairs of maxilla? is the same as in Ilippa, 

 but there are important differences in the details of the foi'ni and 

 structure of special parts, particularly in the posterior lobe of the 

 protognath in the first pair of maxilla?. 



The mandibles (Plate XL VII, fig. 9) are consolidated with and 

 closely invest the walls of the oral opening as in Hippa, but the 

 j)rotognathal portion («) is farther removed from the opening, is even 

 more rudimentary, its margins are unarmed, and it apparently serves 

 only as a base for the attachment of the palpus. The free margin 

 (b) of the outer portion of the palpus projects in an obtuse angle in 

 front and is armed with a few, very stout, short, and obtuse spines. 

 The inner portion (<•), lying just above the labrum, is somewhat 

 orbicular, and its terminal margin is armed witli numerous, exceed- 

 ingly long setie, of which the longest are plumose. 



The terminal portion of the posterior lobe in the first pair of max- 

 illae (Plate XL VII, fig. 10, «) is a thick, heavily calcified, rectilinear 

 plate united, by a broad articulation, with the basal, rod-like portion 

 and at the posterior angle, directly with the buccal walls. Its 

 terminal margin is armed externally with a series of five, very large, 

 short, stout, conical, dentiform spines, and at the angles at each end 

 of the scries with a similar, but very much smaller spine. Upon the 

 short posterior margin there are several still smaller spines of the 

 same character. The terminal margin beneath is thickly beset with 

 stout, plumose setae projecting inward. The anterior lobe [b) is long, 

 very narrow to near the expanded, spatulate extremity, the convex 

 terminal margin of which is densely armed with setae which are stout 

 and spiniform, except anteriorly where they are long and more 

 slender. The palpus (c) is nearly the same as in Ilipjm, but a little 

 shorter and thicker. 



The different parts of the second pair of maxillae are arranged in 

 the same way as in the Hippa, but the posterior lobe of the proto- 

 o-nath is pi-oportionally much smaller and its edge is armed with very 

 lono", plumose sette, which are of nearly uniform thickness to very 

 near the tijis ; while the anterior lobe is spatulate in form and thickly 

 armed with similar, but somewhat shorter, seta-. 



