142 UNITED STATES NATIONAL MUSEUM BULLETIN 296 



were elongate-elliptical, subroimded elliptical, arcuate-elliptical, 

 elongate-elliptical with a slight constriction near the middle suggesting 

 a figure 8, subplanulate, and elongate-elliptical ^\^th an anterior 

 flexure or "hook" due to the presence of a peduncular slit or groove. 



Joysey (1959) described 17 burrows in the test of the echinoid 

 Echinocorys from the Cretaceous Chalk of Culver Cliff, Isle of Wight, 

 Great Britain, in association with. 6 other kinds of burrows. The 

 burrows have the general shape of a somewhat laterally compressed 

 shoe, with the aperture of the burrow and shoe corresponding. The 

 burrow is elongate oval in shape, almost slit-like. No dimensions or 

 measurements are given. Measurements from the figures indicate a 

 maximum burrow length and width of 2.1 and 0.83 mm, respectively. 



Schlaudt and Young (1960) describe a questionable acrothoracican 

 from Permian fossils from the Glass Mountains of Trans-Pecos, 

 Texas, on several species of brachiopods. Their apertures are elliptical, 

 straight, with slight angulations at the loci of greatest curvature. 

 They are 0.6-1.0 and 0.3-0.5 mm in length and width of the burrows, 

 respectively. The burrows completely penetrate the shell, which adds 

 doubt as to their nature, although poor preservation could account 

 for this feature. 



Rodda and Fisher (1962) give an excellent account of what is 

 probably several undescribed species of upper Paleozoic acrothora- 

 cican barnacles from Texas, as well as a useful review of previous work. 

 The reader is referred to this paper for additional information. The 

 only caveat is that the "anterior" end of the aperture, as used by 

 paleontologists, refers to the anterior end of the attached larva, and 

 is more the dorsal or rostral end of the mature barnacle. A good 

 bibliography of articles with plates showing apparently acrothoracican 

 burrows is included. 



Zapfe (1936) describes some fossil burrows with acrothoracican 

 characteristics resembling those described for Lithoglyptes indicus, in 

 Pyrula cornuta of the Helvetian (Miocene) of Varpolata, and in 

 Fasciolaria tarbelliana and Triton nodiferum from the Helvetian of 

 Grund. These two localities are in the Mediterranean, where living 

 L. indicus is completely absent. The dimensions of the burrows in 

 the Fasciolaria shell are as follows: length of opening 3.5 mm, greatest 

 width 1.2 mm, depth 5.3 mm. These agree favorably with the meas- 

 urements of Lithoglyptes indicus burrows, stated by Aurivillius as 4 

 mm long and 6 mm deep, but since so many acrothoracicans have 

 these approximate dimensions, the identification must be regarded as 

 nothing more than a guess at this time. 



Through geological time, the acrothoracicans have apparently 

 changed their major host types several times, each time infecting 

 the thickest-shelled animals available. For example, they seem to be 



