SPURILLA BRAZILIANA MAC FARLAND 93 



Foot. The foot is rather narrow, tapering posteriorly into 

 a short bluntly pointed tail. The anterior margin is thickened, 

 with a distinct, median groove, its outer angles are short and 

 pointed (PL XVI, fig. 85). The total length of the foot is 18.5 

 mm., the diameter of its anterior portion 3.5 mm., narrowing 

 to 3.0 mm. about midway of its length. 



Pharyngeal bulb. The pharyngeal bulb is nearly oval in 

 outline, broadest on its upper posterior border, the sides sloping 

 toward each other below. In front the dark brown hinge portion 

 of the mandibles is thickened and conspicuous. Its maximum 

 measurements are, length 3.0 mm., breadth 1.8 mm., and height 

 1.8 mm., being fully one-third smaller than the pharyngeal bulb 

 of specimens of Sp. neapolitana of the same dimensions of the 

 body. 



Mandibles. The mandibles (PI. XVII, figs. 92, 93), are 

 similar in general form to those of Sp. neapolitana, but decidedly 

 smaller. They are elongate oval in outline, 3.0 mm. in greatest 

 length by 2.0 mm. in greatest width. Each mandible is made up 

 of three portions, the head, the body and the masticatory process. 

 The head is massive, strongly arched in front and below, and 

 bears the fulcrum, or hinge (PI. XVII, figs. 92, d., 93, e.}, a 

 strong dark yellow curved ridge, its concavity directed downward. 

 In the left mandible the crest of this ridge is single (PI. XVIII, 

 fig. 95, c.}, fitting into a groove between the diverging double 

 crests of the corresponding ridge of its fellow of the opposite side 

 (PI. XVIII, fig. 94, c.). 



The body is elliptical, thin, and strongly arched in front, 

 less so behind, its whole extent strongly marked by the 

 lines of growth, parallel to the posterior border. Its inner 

 face is concave, the outer convex. The masticatory process is 

 made up of a triangular lamina, widest behind, attached to the 

 ventral margin of the body of the mandible. Its posterior end 

 is free from the mandible and is separated from it by a deep 

 sinus (PI. XVII, figs. 92, 93, c.}. The ventral margin (PI. XVII, 

 figs. 92, 93, b.) is much thickened and broader, and is prolonged 

 forward, curving upward and backward to the posterior end of 

 the fulcrum (PI. XVIII, figs. 94, 95, d.). It serves as the masti- 

 catory margin of the mandible, and shows no trace of the 

 denticles characteristic of the other species of Spurilla. 



