Subjar/illies, Genera, and Subgenera— Recent and Fossil 93 



of Planorbidae. The figure on plate 50 agrees with that by Pilsbry 

 (1934, p. 57). 



The raclula formiUa is 31-1-31 to 33-1-33 with 182 rows of teeth (plate 

 68, fig. 5) . The center tooth (60) is wider than high, the lower outer corners 

 of the base of attachment expanded to the extent that the base is twice as 

 wide as the summit of the tooth. There are two sharp, spade-shaped cusps 

 which extend below the lower margin of the base of attachment. Lateral 

 teeth (1-13) asymmetrical, tricuspid, the cusps sharp, subequal, and 

 extending below the base of attachment. The intermediate teeth (14-15) 

 differ from the lateral teeth in having either an extra interstitial cusp 

 between the ectocone and mesocone (14) or an interstitial cusp as in 14 

 and an extra cusp above the ectocone. Marginal teeth ( 16-26) elongated, 

 oblique, the mesocone remaining a large sharp cusp, but the entocone 

 splitting into three to five small, subequal cusps arranged obliquely. The 

 ectocone continues as a large cusp but above it, on the' margin of the tooth, 

 there are three to six very small cusps in addition. The ectocone is always 

 separated from the mesocone by a distinct gap. The small cusps above the 

 ectocone are placed higher up on the tooth than in other genera. The outer 

 marginals are very narrow and oblique and the cusps appear as minute 

 serrations. Even here, however, the two groups of cusps, mesocone and 

 ectocone, are separated by a considerable space. 



Pilsbry (1934, p. 55) figures the radula of the race christopherensis 

 which agrees in all essential details with the figures on plate 68. He gives 

 the formula as 30-1-30 with seventeen laterals. In specimens personally 

 dissected the marginals began on the 16th tooth in two specimens and 

 on the 18th tooth in one specimen, the 15th to 17th teeth being intermediate 

 in character. These differences are unimportant. 



Scott (1940, pp. 10-12) figures the radula of specimens from Caracas, 

 Venezuela, and Puerto Rico, showing great variation in the form of the 

 cusps. The Venezuela form with a formula of 45-1-45 may be represen- 

 tative of the race oUvaceus. 



The material used for this anatomical study was received from Dr. 

 Wm. A. Hoffman and was collected at Lares, Puerto Rico. 



Geographical Distribution. Except for its occurrence in Haiti, Puerto 

 Rico, and the Caribbean islands, Avstrcdorbis is a South American group 

 (Pilsbry I. It is known in South America from Venezuela southward to 

 Argentine Republic. 



Species Considered as Valid. ]\Iany names have been given to varia- 

 tions within this genus and consequently there are many synonyms. The 

 following species and races appear to be recognizable: 



Australnrbifi ginbratus (Say) (= Quadaloupensis Sowh.) 

 Australorbis glabratus christ ophcren.fis Pilsbry 

 Australorbis glabratus oUi'accus (Spix and Wagner) 

 Australorbis glabratus refulgcns (Diinker) 

 Australorbis glabratus higubris (Wagner) 

 Australorbis glabratus blauncri (Germain) 

 Australorbis antigucnsis (Sowerby) 

 A ustralorbis itn 7)i unis ( Liit z ) 

 Australorbis bahiensis (Diinker) 

 Australorbis tenagophilus (Orbigm-) 



Geological Distribution. This genus probably dates fi'om the Oligocene 

 or Miocene period of the "West Indies and South America. 



