THE BURROWING BARNACLES (CIRRIPEDIA: ACROTHOR ACICA ) 41 



chrysostoma L. from Koror Island, collected in 1948 by Daniel B. 

 Langford, from the Bernice P. Bishop Museum sheU 204337. 



Type-material: Holotype: USNM 122604. Paratypes: Aust, 

 Brit, SFSC. Additional material: BPB, Belg, BA, CA, Dublin, Mex, 

 Paris, UCT, Vict. 



Dimensions: The holotype specimen is 2.33 X 1.33 mm in length 

 and width, with an aperture of 1.25 mm. The average size of nine 

 specimens (five type-specimens plus four selected mature females) is 

 2.36 X 1.46 mm length and dorsoventral width, with an attachment 

 disk 1.12 mm wide and an aperture 1.26 mm long from apex to attach- 

 ment end, in 70-percent alcohol. 



The FEMALE : The mantle is equipped with transverse and longitudi- 

 nal bands of muscle, and armed with numerous smaU teeth distributed 

 over the surface, especially on the ventral aspect and near the aperture. 

 The teeth may be many-pointed, with two or three points the most 

 common. One tooth with five points was seen, and is included in 

 figure 3a. 



The apertural plates, analogous to the operculum, are heavy, broad, 

 and flat, tapering at the apex to curved points, but not bearing major 

 hooks or heavy spines. Both margins of both plates are armed with 

 approximately 20 to 35 fine teeth. The teeth of the outer margin are 

 usually bifid, or two-pointed, although an occasional simple tooth is 

 found. The teeth on the inner margin are more finely divided, with 

 three- and four-pointed teeth common. Across the outer face of the 

 opercular plates are scattered other teeth, which appear to be the 

 culmination of reinforcing ridges laid out in a reticulated pattern. This 

 pattern is seen more clearly on the medial external surfaces of the 

 plates. Rows of fine dots ornament the plates, and long but rather 

 flexible hair-Hke bristles are scattered along the length of the plates, 

 especially on the outer or lateral edges. The typical comb collar 

 membrane is adherent to the inner surface of the mantle, and projects 

 as convoluted bristle-Hke extensions between the plates apically. 



The color of the mantle in hfe is a bright brick red, concentrated 

 about the apertural area. A Ughter band is found traversing the 

 operculum shghtly dorsal (toward the attachment end) of the middle. 



On the mantle surrounding the apertural area are fine scale-like 

 markings, scattered with small simple teeth set on heavy, round bases. 

 A few very fine hair-like bristles are scattered about in this area. The 

 scaly portion of the mantle extends posteriorly on both sides in the 

 region where the lateral bar is found in those species bearing this 

 structure, and perhaps this scaly material is an evolutionary beginning 

 of the lateral bar. 



The head is rounded, backed on the dorsal side by a pointed crest, 

 and the whole is set with irregularly arranged small hairs. 



