PARASITIC COPEPOD CRUSTACEANS — LEWIS 



129 



and lateral to postoral process. First and second segments of ap- 

 proximately equal length, fii'st more strongly developed, with 

 tapered and curved proximal end forming articulation and muscle 

 attachment surface; second segment elongate, narrower proximally 

 than distally, with pair of saber-shaped terminal processes, inner 

 approximately twice the length of outer, with pair of fine, filmy 

 membranes, outer terminal process with fuzzy membrane along inner 

 and outer lateral margins. 



Ventral smface of cephalothorax with several irregularities, 2 of 

 notable value. First a lobate projection (fig. 31e) of heavily sclerot- 

 ized ridge extending laterally from base of antenna. Second a pair 

 of minute, subtriangular projections (fig. 32a) between maxilla bases 

 and just anterior and medial to maxilliped bases, in region of postoral 

 adhesion pads found in pandarids, euryphorids and some caligids. 



Table 13. — Armature of thoracic legs I-IV of the female of Trebius caudatus 



Kr^yer, 1838 



*SmaU, hairlike spicules on protopodite and exopodite not included. 



Maxilliped (fig. 32a) 2-segmented, situated posterior and medial 

 to maxilla base. Fkst segment longer than second, with spikelike 

 projection from posteroproximal surface. Second segment slender, 

 tapered slightly from proximal to distal regions, with small, clawlike 

 terminal process distinct from segment, also with setule-like acces- 

 sory processes adjacent to terminal process. Sternal furca (fig. 32a) 

 large, situated between and slightly posterior to maxilliped bases, 

 consisting of anteriorly rounded, heavily sclerotized plate bearing 

 pair of slightly diverging tines, tines approximately one and one- 

 fourth times the length of plate. 



Thoracic legs I-IV biramous, protopodite 1-segmented, rami of 

 first leg 2-segmented, of others 3-segmented. For nature of armature 

 and legs see table 13 and figm'es 326-/. 



