60 UNITED STATES NATIONAL MUSEUM BULLETIN 296 



Dimensions: Koror females 2.0 X 11 mm wath apertm^e of 0.77 

 mm, other specimens respectively 2.0 X 0.9 X 0.73 and 1.35 X 0.95 

 X 0.49 mm. Males from Wake Island measured: youngest 0.33 X 

 0.14 mm; adults 0.48 X 0.18, and 0.63 X 0.26 mm. 



The mantle bears the conspicuous operculum and its armament, 

 an extensive cemented disk to which males are attached, the usual 

 internal comb collar, and scattered external teeth which are usually 

 single spines or bifid teeth, although they are rarely three- or four- 

 pointed. 



The operculum bears a pair of elongated spines, which curve gently 

 toward the attachment area. This spine is in turn equipped \vith a 

 few teeth and hairs. Bifid teeth are arranged along the entire oper- 

 culum. It is noteworthy that in all three specimens from Koror a 

 prominent bifid tooth is situated near the center of the operculum 

 on each side (fig. lib). The Wake Island material did not show this 

 (fig. 11a). 



There is no lateral bar or orificial knob in the species. The former 

 is suggested by extremely faint scales on the surface of the mantle, 

 but is not considered functional. The orificial knob in other species 

 of Lithoglyptes is a toothed projection between the operculum and 

 the attachment disk. The operculum is reinforced by a strong chi- 

 tinous dorsoposterior extension from the posterior end. 



The body is typical of the genus. One pair of biramous mouth cirri, 

 four pairs of biramous terminal cirri, and a pair of uniramous caudal 

 appendages are present. The segmentation of the mouth cirri is ob- 

 scure. They appear to be composed of three and two segments on a 

 weakly two-segmented protopod. The terminal cirri are also on two- 

 segmented protopods, with the cirri composed of 18 to approximately 

 38 segments in the Koror material, with the lower numbers in the 

 first terminal cirrus. A Wake Island specimen had the following 

 segment count: 



The caudal appendage is clearly two-segmented. 



The mouthparts consist of the usual paired mandible with palps, 

 and two pairs of maxillae (fig. llf). The labrum serves as an upper 

 lip of the mouth field, and is rounded and heavy. The mandibular 

 palps are simple with several hairs distaUy, although they appear 

 adherent to the labrum as much as to the mandible. The mandible 



