HAWAIIAN ACANTHURID CALIGOIDS — LEWIS 139 



The term "genital segment" designates the fused fifth and sixth 

 thoracic leg-bearing segments. 



In the descriptions of all but two of the species the second antenna 

 is described as three-segmented. This is in opposition to many of 

 the earlier, and some of the present-day, workers. The author is 

 accepting the viewpoint at this time that the segment attached to 

 the ventral surface of the cephalothorax along most of its proximal 

 surface is a distinct segment. 



The spinelike projection just lateral and posterior to the base of 

 the second antenna is called here the postantennal process; the 

 spinelike projection just lateral to the base of the mouth cone, the 

 postoral process. With this terminology, the two pairs of appendages 

 between the mouth cone and the first thoracic legs become the max- 

 illae and maxillipeds respectively. Applying the term "postantennal 

 process" to the structure immediately behind and lateral to the second 

 antennae is in opposition to Wilson (1905), Heegaard (1947), and 

 others who apply the term "first maxilla" to the process. Excluding 

 the word "cuticular" from the term "postantennal process" is in con- 

 trast with Gurney (1927), Lang (1948), and others, but indicates the 

 present author's desire neither to accept nor to reject the belief that 

 the process is not a true appendage. The application of the term 

 "postoral process" to the structure immediately lateral to the base 

 of the mouth cone is in contrast to all other workers who term the 

 process a "maxilla." Both the postantennal and postoral processes 

 are unsegmented, spinelike structures innervated by subesophageal 

 nerves that arise from the same region of the ganglion (Scott, 1901; 

 Wilson, 1905; Lewis, unpublished). Each process possesses at least 

 one setule-bearing nodule. The fact that there is no evidence of 

 segmentation suggests that these structures are not true appendages. 

 Although both are innervated by subesophageal nerves, these nerves 

 arise in close association to each other and in association with a sub- 

 esophageal nerve that innervates parts of the body musculature and 

 not the musculature associated with any of the oral appendages. 

 The presence of at least one setule-bearing nodule may or may not 

 offer evidence that the processes are appendages, since single setules 

 are found on parts of the body not associated with any appendage. 



The mandible here is considered "parted," not segmented. The 

 exact derivation of the adult mandible is not known but the lack of 

 distinct musculature and the indistinct divisions among the parts 

 indicate that a true segmented condition does not exist in the adult 

 appendage. 



The term "chitinized," as here used, is synonymous with the term 

 "sclerotized." 



