226 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 115 



mann in the family Chondracanthidae although Bassett-Smith (1899) 

 and Wilson (1922, 1932), recognizing its affinities with members of the 

 Caligoida, placed it in the family Dichelesthiidae. The overall 

 appearance of the body and the specific appearance of the oral append- 

 ages and the cephalothorax indicate its relationship to species of 

 Anthosoma, Lernanthropus, and Sagum. Norion differs from these 

 genera by its extreme dorsoventrally flattened condition, the paired 

 ventral plates that are neither bifid nor produced, and the reduced 

 first thoracic legs. Because of the similarities of the four genera, 

 Norion is placed in the family Anthosomatidae with these genera, 

 the latter originally being a subfamily of the family Dichelesthiidae. 



Norion expansus Nordmann 



FiGtTRES 22a-c, 23a-k 



N. expansus Nordmann, 1864, pp. 489-491, pi. 6.— Bassett-Smith, 1899, p.469. — 

 Wilson, 1922a, pp. 26-27. 



Present hosts (original host unknown). — Naso lituratus (Bloch and 

 Schneider), Ndso hexacanthus (Bleeker). 



Distribution. — Hawaii. 



Material. — Adult female collected by author from gill lamellae 

 of specimen of Naso lituratus (Bloch and Schneider) speared by author 

 off Lehua Rock, Niihau, Hawaii. Two adult females collected by 

 author from gill lamellae of two specimens of Naso hexacanthus 

 (Bleeker) taken in fish traps between Diamond Head and Koko Head, 

 Oahu, Hawaii, by Samuel Kaolulo. Two adult females collected by 

 Dr. Hilda Ching from gill cavity of unknown species of Naso speared 

 by Edgar Hookano off Kahuluu, Oahu, Hawaii. (USNM 105113- 

 105116.) 



Measurements. — Average of greatest length 7.91 mm.; range 

 6.52-9.02 mm. Average length from anterior margin of head to 

 posterior margin of body 6.72 mm.; range 5.70-7.91 mm. Average 

 of greatest width 6.07 mm.; range 5.15-7.36 mm. Average length of 

 fused cephalon, maxilliped-bearing segment, and first thoracic leg- 

 bearing segment 1.29 mm.; range 1.10-1.56 mm. Average of greatest 

 length from anterior end of second thoracic leg-bearing segment to 

 posterior end of caudal rami 2.76 mm. ; range 2.21-3.95 mm. Average 

 of greatest length of single posterior dorsal plate 5.06 mm.; range 

 4.32-5.98 mm. Average of greatest length of paired dorsal plates 

 3.86 mm.; range 3.22-4.51 mm. Average of greatest length of paired 

 ventral plates 5.43 mm.; range 4.51-6.90 mm. 



Description. — Body yellowish brown in life, with fine, lighter 

 colored vessels around margins of plates. Vessels filled with red 

 fluid in living specimens that may form part of circulatory system ; fluid 

 flowing intermittently in response to movement of animal. 



