BRACHIOPODA. 
81 
impressions in Obolella which have been designated by this term, but more 
nearly to that of the terminal scars of the crescent in Dinobolus. The median 
area of the valve on each side of the septum is much thickened, and at its 
anterior edge lie the conspicuous central scars. In the brachial valve the 
cardinal and “lateral” (external or terminal) impressions are developed as in 
the opposite valve, and in the central region is a pair of curved impressions 
suggestive of, and probably corresponding to the elongate laterals in Obolella. 
These enclose an indistinct central scar. 
The affinities of Obolus with the linguloids are somewhat remote and general, 
but are seen in the character of the cardinal area and the disposition of the 
central muscular scars in the pedicle-valve. The strongly thickened median 
area of the same valve, which is given prominence by the excavated central 
scars, is suggestive of a rudimentary platform such as is found with greater 
development in Lingulops, Lingulasma and the Trimerellids. This, however, 
may be an homology only, as the muscular scars in Obolus are not situated 
upon, but at the anterior margin of this area. The external muscular impres¬ 
sions with the ridge proceeding from them backward, toward the umbo, suggest 
the crescent in Dinobolus, and are the equivalents of the terminal crescent 
scars in that genus and the externals in Obolella, while the curved laterals in 
the brachial valve show, as just noticed, the near relationship to the latter 
genus. 
A species from the St. John group, at Calun’s Island, King’s county, New 
Brunswick, has been referred to this genus by Mr. G. F. Matthew,* but we 
have, as yet, no knowledge of its interior characters, and the reference requires 
verification. The exterior of both valves of this shell is ornamented in the 
umbonal regions by a reticulated punctation which is apparently superficial. 
This becomes obsolete with the later growth of the shell. (See Plate IV k, 
fig- 22.) . ' 
* O. pulcher, Matthew. Canadian Record of Science, January, 1889, p. 306. 
