524 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 112 



surface of the mantle around the aperture and on the base of the hooks 

 and spines. The remainder of the mantle is naked. 



The attachment disc adheres strongly to the burrow, and the 

 barnacles are not readily removed until the coral is decalcified. From 

 the base of a groove formed by the heavily reinforced ridges between 

 the disc and the aperture, a small duct opens to the exterior from what 

 is believed to be a cement gland. 



The average length of the slitlike aperture, based on 12 specimens, 

 is 0.63 mm. Two large curved hooks are situated at the dorsal rim, 

 and two large straight spines are situated near the ventral rim of the 

 aperture. The hooks are essentially immovable while the spines, al- 

 though not jointed along their length, have flexible basal attachments 

 and can be opened outwardly in dead specimens from their usual 

 position over the aperture. Comblike projections extend upward 

 from both inside edges of the aperture and tend to occlude it. 



The pharynx leads dorsally from the mouth. The gut then bends 

 posteriorly as an esophagus which leads to the long stomach. A 

 supraesophageal ganglion is situated just dorsal to the esophagus. 

 A pair of round digestive glands arise from the ventral side of the 

 stomach and project anteriorly. An unpaired, thick-walled pocket 

 near the anus may represent a rectal gland. The elongate anus opens 

 between the paired terminal cirri on the dorsal side of the body. 



The mouth parts (figs. 5-7), composed of mandibles with palps and 

 two pairs of maxillae, are typical for the genus. Each mandible has 

 three strong, equally spaced teeth and numerous short spines and 

 bristles on the cutting edge. The mandibular palp exceeds the 

 mandible in length, and terminates in a tapering point; the edges bear 

 a few long, soft bristles. Each first maxilla is armed with two strong 

 teeth, numerous bristles and short teeth along the cutting edge, and 

 is equipped with the usual apodeme. The second pair of maxillae 

 are large and soft and have numerous flexible bristles distributed along 

 their edges. These appendages are set close together and serve to 

 cover the mouth field. 



The mouth cirri (fig. 8) have a 2-jointed pedicle upon which the two 

 bristle-bearing rami articulate. They arise below the mouth parts 

 and can extend up to the aperture of the mantle. They normally 

 curve with the tips directed outward from the body. The anterior 

 ramus has five segments, and the posterior ramus has four segments. 

 All segments of the rami are equipped with numerous bristles arising 

 with no particular symmetry. Many of the posterior bristles are 

 hairy or feathery. 



There are four pairs of biramous, multisegmented terminal cirri. 

 The articulations between the segments of the pedicles are slanted 

 obliquely (fig. 9), a characteristic of the genus noted by Aurivillius 

 (1892). The number of articles of the rami range from 30 to 50 



