THE BURROWING BARNACLES (CIRRIPEDIAI ACROTHORACICA ) 75 



Reinforcing these plates are two lateral bars extending posteriorly 

 from about the middle of the apertural plates. These lateral bars are 

 finely reticulated, and are not associated with rows or patches of 

 teeth on the mantle. 



The major muscle masses are present to varying degree in the 

 attachment area. I consider two thin and weak-looking muscles from 

 the orificial knob extending toward the attachment disk as the 

 retractor pallii rostralis, although this muscle is considerably weaker 

 than in other members of the genus. The retractor corporis is a large 

 muscle connecting the orificial knob and the dorsal body area, whUe 

 the retractor oriUcii extends from the attachment area to the orifice, 

 with slips into the origin of the retractor corporis in the orificial knob. 



The head is rounded and studded with one or more rows of fine 

 hairs. Fine scale-like lines are seen between the hairs. 



The mouthparts are typical for the order: a pair of mandibles with 

 palps, and two pairs of maxillae (fig. 15c). The unpaired labrum at 

 the anterior mouth field leads into a long tubular esophagus. The 

 labriun is saddle shaped with reinforcing curved rods extending from 

 each side which are perhaps typical of the genus, and fine granulations 

 which often form rows of dots. 



The mandible is equipped with two to four major teeth, plus an 

 inner lower angle with numerous fine teeth and bristles. This angle 

 also is bristled on the lateral surface (fig. 15d). The variability in 

 number of major teeth is not common in the order, and does much to 

 destroy the value of the feature as a taxonomic characteristic. Often the 

 left and right mandible of one female will differ in the number of these 

 teeth. A heavy extension of the base of the mandible is apparently an 

 apodeme, but is shorter than the apodeme of the first maxilla, and is 

 not hooked. The mandibular palp is closely adpressed against the 

 labrum. It is edged on the inner margin with a row of hairs. 



The first maxilla is typical of the order, bearing two major teeth 

 on the superior outer margin, a gap or diastema usually broken by a 

 couple of bristles, then a rounded margin with numerous very fine 

 teeth and heavy bristles. A long curved or hooked but variable 

 apodeme supports the base of this maxilla in typical fashion (fig. 15e). 



The second maxilla forms the typical triangular-shaped, heavily 

 haired bottom of the mouth field. 



The first pair of cirri (mouth cirri) are located directly posterior 

 to the mouth field, and curve anteriorly on a long two-segmented 

 protopod. The shorter distal segment is lightly bristled and bears 

 a pair of rami with a variable number of segments. The anterior ramus 

 is longer, and bears four segments, while the posterior ramus has 

 either three or four, although segmentation can be obscure, especially 

 in this genus. Both rami are heavily bristled. The bristles are faintly 



327-241 O - 69 - 6 



