88 CEETACEOUS PELECTPODA 



55-56.- — P. acuminata ( ? Homomya) and P. ^^w^^m are described by Sehafhseutl from the 

 same beds in which cretaceous fossils according to him also occur, but the exact position of the fossil 

 is unknown (see Siid-Bayern^s Leth. Geog"., 1863, p. 174). 



57-58. — P. rustica MAfrequens, Zittel, are from the Alpine Gosau formation (Denksch. Akad., 

 Wien, 1865, XXIY, pt. II, p. 110, &c.). The first in form somewhat resembles Sowerby's 

 laviuscula, the second may be, as already stated, a Toromya, 



Eichwald (Leth. Eoss., XI, 1867, p. 781, &c.,) also mentions from the cretaceous beds 

 of Russia P. regularis and sU'iata (==suistriata) . 



59. — Bosquet (Staring's bod. v. Nederland, II. deel,) quotes, besides P. Goldfussi and 

 UsmarJci, a P. Santi-Petri ; 1 am not acquainted with that species. 



60-67.— Meek (Smith. Mis. Coll., No. 177,) quotes from North America P. decisa, Newhenyi, 

 occidentalism suhplicataj suhparallela, texana^ Tuomeyi ? Facliymya attstenensis, which is more probably 

 a species of the Myiid^j (see p. Q1), and Pan. concentrica, Gabb., from the Californian cretaceous 

 deposits ; this last is, however, subsequently (Pal. Calif. II) referred by its author to Homomya. 



P. decisa of Conrad has been referred by Gabb to Gyrtodaria {= G lycimer is), hut \mle^^ 

 Conrad^'s figure and description is very incorrect the species cannot belong to that genus. 



68.— Conrad describes (in Offic. Eep. of Lynch's expedition to Palestine) P, pectorosa diwdi 

 orientalis, which I only know by name and cannot say whether the second one is considered identical 

 with the Indian species. 



69. — P. orientalis, Forbes, is the only species which occurs in Southern India. 



70. — P. Nagorzanyensis, Favre, (Desc. Moll. foss. de Lemberg, 1869, p. 104, pi. xi, fig. 9), is 

 from the upper cretaceous beds of Galicia. 



SAXICAVA, FL d. Bell, 1822, (see p. 84). 



\/ 1. Saxicava tenella, Stoliczka, PI. XVI, Eigs. 20-24. 



Sax. testa transversaliter elongate-ovata, incequilaterali, pertenui, umbonibus 

 minutis sub-anticis, in superficie striis minutis mcrementi instructa ; valvtilis sub- 

 incequalibus, moderate tumidis, dextra paulo majori; cardo in valvula dextra 

 dentibus diiobus quorum superior minutus, in vaL sinistra dente unico insti^uctus, 

 nymphis parvulis. 



Height of shell : its length ... ... ... ... 0"58 



Thickness „ : „ ... ... ... .., 0-22 



The shell of this species is remarkably thin, sometimes almost hyaline, very 

 jfinely concentrically striated ; the beaks are prominent and situated at nearly one- 

 third of the total length from the anterior margin ; the right valve is a little larger 

 than the left, as, for instance, in adult specimens of the recent S. similis, Desh. ; 

 the hinge in the right valve has two teeth, one stronger below and a little in front of 

 the beak, and one smaller above and anterior to it, the latter being, strictly speaking, 

 only a slight projection of the shell margin ; the left valve has one small tooth 

 below the beak ; the nymphse are small, but more distinct in the left than in the 

 right valve. 



Locality. — North of Odium, not uncommon in a dark brown somewhat sandy 

 limestone. 



formation, — Ootatoor group. 



