168 *, PROCEEDINGS _OF THE ACADEMY OF [March, 
Guadalupe river 6 to 4 miles to the north; San Marcos river at San 
Marcos, Hays county, on the dam above the fish hatchery (Pilsbry 
and Ferriss; Singley); a variety from Bexar county (A. G. Wetherby). 
This form differs from Melania pluristriata Say (M. rubida Lea) of 
central Mexico, by its far smaller size and less ample aperture. The 
type of pluristriata measured 1.25 x .55 inches; of rubida 1.30 x .57 
inches; and the specimens from Lake Chapala examined by Dr. von 
Martens from 26 x 12 to 35x 13 mm., while no Texan shell we have seen, 
in many hundreds examined, reaches 1 inch long. Von Martens refers 
the Mexican species to Pachycheilus. Dr. William H. Dall, to whom we 
submitted specimens of G. comalensis for comparison with the type of 
M.rubida Lea, writes that ‘‘though the general form is the same, the 
rubida is very much larger and perfectly distinct.’? The examples 
figured are from Comal creek, New Braunfels, near the mill. 
The ascertained distribution of G. comalensis comprises only the 
short rivers of a single small system emptying into Espirito Santo Bay, 
intercalated between the Colorado and Nueces basins, and comprising 
the Guadalupe and San Antonio rivers and their tributaries. 
The Goniobases are known from these streams only at the edge of 
the ‘‘Edwards Plateau.’’ As they live on rocks, etc., in swift water, 
it is not likely that they approach much nearer to the Gulf. In the 
Fig. 30. Fig. 31. 
Colorado river, where Filsbry collected in 1885, nothing was seen of the 
species, nor has it been reported from the Nueces or its branches. We 
saw no sign of Goniobasis in the tributaries of the Rio Grande, where 
our collecting was extensive enough to have found it if it existed.” 
The operculum (fig. 29) consists of about four whorls, the nucleus 
being situated at about the lower third of its length. It is closely 
™ 12 Tn the collection of the Academy there are several specimens labelled ‘‘ Dal- 
las county,’’ received from Mr. J. A. Singley. This is in the Trinity river 
drainage, but Singley in his catalogue of 1893, issued long after these specimens 
were placed in the collection, expressly states that he found the species nowhere 
but in Comal and Hays counties. There was probably some error in labelling 
the specimens. 
