1892.] NATURAL SCIENCES OF PHILADELPHIA. 403 



Genus ANOGLYPTA Martens. 

 Hedley, Proc. Linn. Soc. N. S. Wales (2), VI, p. 22, 1891. 



Genitalia simple as in Trochomorplia ; jaw and teeth also resem- 

 bling that genus, from which this is sundered mainly on account of 

 the peculiar shell. 



Distribution, Tasmania. 



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Group VI, POLYPLACOGNATHA. 



Genitalia lacking all accessory organs ; jaw composed of numer- 

 ous separate quadrangular plates ; lateral teeth bicuspid. 



Genus PTJNCTUM Morse. 



Genital system like Patula. Jaw composed of about 16-19 sepa- 

 rate quadrate plates. Dentition : central teeth unidentate, laterals 

 bi dentate. 



Shell discoidal, with round, ci-escentic aperture, and thin, acute 



lip- 



Distribution, Holarctic realm. 



Differs from Microphysa, etc., in having the plates of the jaw 

 actually unsoldered, but connected by a delicate membrane. 



Genus LAOMA (Gray) Pils. 



Genital system unknown. Jaw composed of 20-24 quadrangu- 

 lar papillose plates. Central tooth uuicuspid, side teeth all bicuspid. 



Shell more or less trochiforra, generally keeled and variegated ; 

 aperture rhomboidal, lip thin, simple. 



Section Laoma s. s., aperture with lamellae within. 



Section Phrixgnathus Hutton, aperture without lamellae. 



Distribution, New Zealand. 



My knowledge of the anatomy of this genus is derived from the 

 writings of Hutton and Suter. The jaw should be compared with 

 that of Fhacussa, Therasia, etc. The lateral and marginal teeth 

 are peculiar and very characteristic. 



Genera of Doubtful Position. 



Genus STROBILOPS Pilsbry. 



Strobila Morse 1864, not Sars 1833. 

 Strobilus Sandberger et al., not Anton 1839. 



Genitalia unknown. Jaw ribbed. 



This genus is represented by many species in the middle and 

 later tertiary of Europe, and by several living species in America, 



