HAWAIIAN ACANTHURID CALIGOIDS — LEWIS 227 



Body ovoid, anterior half, except cephalon, maxilliped-bearing seg- 

 ment, and fii'st thoracic leg-bearing segment, covered dorsally by 

 pair of plates projecting anteriorly on either side of head and form- 

 ing U-shaped depression from apex of which uncovered cephalo- 

 thoracic portion of body projects. Anterior margins of projecting 

 plates broadly rounded, posterior medial margins irregularly convex; 

 anterior dorsal plates attached to dorsal and lateral surfaces of sec- 

 ond thoracic leg-bearing segment. Posterior dorsal portion of body 

 covered by single, broad plate projecting posteriorly past caudal 

 rami for distance equal to length of entire body, excluding plates. 

 Lateral margins of single dorsal plate tapered to evenly rounded 

 posterior end. Lateral margins broadly rounded anteriorly; ante- 

 rior margins slightly concave, curving anteriorly to evenly rounded 

 anterior median apex. Posterior lateral surfaces of paired dorsal 

 plates overlapping anterior lateral surfaces of single plate. Single 

 posterior dorsal plate attached along entire dorsal surface of third 

 thoracic segment. Second thoracic legs greatly expanded, forming 

 platelike structures covering entire ventral surface posterior to ceph- 

 alothorax, extending posteriorly almost as far as posterior dorsal 

 plate and anteriorly, along ventral surface of pah-ed dorsal plates, 

 to middle of cephalothorax. Second thoracic legs and posterior dorsal 

 plate form brood pouch. Dorsal and ventral plates attached along 

 adjacent margins by membranes. Surface of all plates covered with 

 minute bmnps (figs. 22a-c). 



Cephalon, maxilliped- and first thoracic leg-bearing segments fused, 

 forming cephalothorax, separated from rest of body by distinct groove 

 though first thoracic leg-bearing segment overlapping second slightly 

 on both dorsal and ventral surfaces (figs. 226, 23a). Cephalothorax 

 oblong, wider than long. Anterior and lateral margins of head irreg- 

 ular. Ventral surface of cephalon with padlike structures on lateral 

 and anterior surfaces leaving central depression from which append- 

 ages and mouth cone arise (fig. 23a). First thoracic leg-bearing seg- 

 ment slender, anterior margin concave on ventral surface; fu'st 

 thoracic legs reduced, forming padlilvc structure, with concave depres- 

 sion on anterior surface to receive maxillipeds (fig. 23a). Second 

 thoracic leg-bearing segment slender, much wider than long, distinct 

 from first thoracic leg-bearing segment and third thoracic leg-bear- 

 ing segment; anterior surface pocket-shaped for rotation of cephalo- 

 thorax. Posterior ventral surface of second thoracic leg-bearing 

 segment heavily chitinized in lateral regions, forming base for modi- 

 fied, platelike second thoracic legs attached to segment by narrow, 

 pedunculate extension of proximal region of legs. Third thoracic 

 leg-bearing segment large, expanded medially, larger than all other 

 segments; lateral margins faint but distinct, tapered into single poste- 



