THE BURROWING BARNACLES (CIRRIPEDIA: ACROTHORACICA) 109 



purple, which extends down the neck of the mantle almost to the 

 attachment area, becoming streaked and lighter in the lower half of 

 the neck. 



The armature of the operculum is awesome. One minor and two 

 major pairs of enormous, pinnately compound spines arise from the 

 lateral edges, and a lesser pair of spiny processes serve as the dorsal 

 end of the opercula (on the rostral, or attachment side). Although 

 there is a lot of individual variation (figs. 28c-h), the basic pattern 

 is the same. The spines are well over half as tall as the operculum is 

 wide. The bases of the spines bear numerous smaller spines, set on 

 collar-like heavier bases of their own. Two to five additional spines 

 between the larger pair are also pinnately compound, with very fine 

 hyaline teeth set on their margins. Long, flexible hairs are scattered 

 over these spines. 



Medial to the main spinal armature, six or more tall, barbed shafts 

 arise like lances from the opercular surface (fig. 28b). These may be 

 slightly curved, but are quite uniform in the width of the shaft. They 

 are set on heavy bosses, but do not appear to articulate. They re- 

 semble commercial crochet hooks. On the ventral end of the mantle 

 aperture (away from the attachment end) the typical comb collar 

 infolds. This is a folded membrane or velum with even, fine crenula- 

 tions which distally appear as a row of minute hairs. 



The mantle along its two sides bears a pair of heavy lateral bars, 

 plus a small reinforcing bar along the dorsal surface. These are rein- 

 forcing convolutions in the mantle chitin, and are typical. Heavy 

 bifid teeth are deployed along the ventral side of the lateral bars, and 

 a characteristic assemblage of teeth are distributed around the pos- 

 terior end of the bar. This latter series consists of about eight simple 

 teeth spread like an island chain in a wide arc, with a curvature 

 opposite that of the lateral bar. 



Another characteristic set of bifid teeth, numbering eight or more, 

 face upward (anteriorly) around the neck just below the operculum. 

 Other teeth are scattered over the surface of the mantle, especially 

 in the ventral half. Some of these teeth can become very complex, 

 with five-pointed teeth common, and a seven-pointed one seen (fig. 

 28m). 



The attachment disk is not as heavy or horny as some other 

 species, but the mantle definitely attaches to the burrow on the dorsal 

 surface. No attachment knobs or orificial knobs are present. 



The mouthparts are typical of the genus. A long labrum extends from 

 the anterior mouth area into the mantle aperture. It is pointed, with 

 many hairs along the lateral edges, and a few scattered shorter bristles 

 on the ventral surface (fig. 28i). A pair of mandibles, with palps which 

 seem to adhere to the labrum, and two pairs of maxillae complete the 



