30 CEETACEOUS PELECYPODA 



21-22.— Gast. americana, GaLb, (Jour. Phil. Acad., 2nd Ser., vol. iv, p. 393, pi. 68, fig. 20), 

 is to all appearance a true Gadrochcena, and the same must be said of the South Indian Fislulana 

 aspergilloides o/" Forbes. 



The CLAVAGEhLiNjE have representatives in cretaceous deposits, belonging to the genera 

 Clavagella and Slirpulina. 



23-26. — Pictet (loc. cit., p. 6,) enumerates four European cretaceous species of Clavagella, 

 C. cretacea, d'Orb., and C. clavata {? Teredina clavata, Eom., sp.), may either belong to Clava- 

 gella or to Slirpulina ; in neither case do the specimens seem to have been sufficiently well preserved. 

 CI. Cenomaniana and CI. Ligeriensis, d'Orb., are known only by their names. 



27-28. — Miiller (Suppl. to Monograph der Petraf. der Aachner Kreidef., 1859, p. 17,) 

 described two species, CI. elegants, which is a Stirpiclina, while the other, CI. divaricata, is very 

 doubtful, being based upon a single valve which is rather different from the usual type of Clavagella. 



29. — CI. cornigera, Schafh. Siid-Bayerns ( Leth. geogn., 1863, p. 179), is apparently a 

 Slirpulina, although the figure does not exhibit any difference in the valves ; it would seem as if 

 both valves were free, or both grown together with the tube ; in the latter case the species must be 

 transferred to Brechites. 



BO.— CI. exigua, Zittel, (Denksch. Akad., Wien, vol. xxiv, 1865, pt. 2, p. 107,) is from the 

 Alpine Gosau-deposits. 



31. — From America only one species is known, CI. armata, Mort., which is very similar to the 

 last, and probably a Slirpulina. 



32, — CI. semisulcata, Forbes, will be described subsequently. 



33. — The only notice of a species possibly belonging to the BRECSITIN^ is by Rominger in 

 Bronn's Jahrbuch f. Min. for 184'7, p. 659, where the author mentions a new species, Aspergillum 

 cretaceum, from the Turonien beds of the county of Glatz. No fm-ther notice beyond the name 

 has been published ; probably the species is the same as the one described by Schafhseutl, noted 

 above. 



Thus on comparing the species of gasthocejENIDje, represented in cretaceous 

 rocks, we find that more than two-thirds belong to the gastsocs^nin^, somewhat 

 less than a third to the clavaqellin^, while the occurrence of sa^c^zzriS'^/E is doubt- 

 ful, and in any case their number would be the smallest. The gastroce^nin^ are 

 already known from the Trias and gradually increase up to the present time ; the 

 cLAVAGELLiN^, howeTer, have not as yet been met in strata older than the creta- 

 ceous. 



V. ROCELLAEIA, Ft. de Bell, 1802, (see p. 26). 



1. ROCELLAKIA GUTTULA, StoUczhci, PL I, Fig. 7. 



B. testa valvis ovato-elongatis, convexiusculis, siihla;vigatis, antice aciiihiscuUs, 

 2)0stice sub-truncatis, valcle incequilateralibus ; hiatu antico magno, lato, postice fere ad 

 di/midium longitudmis extenso ; tiibis breoibus, regularUer ovatis, antice rotundatU, 

 postice rapide contractis, atqiie breviter prolongatis. 



The tubes formed by this species are very characteristic ; they are regularly 

 ovate, inflated, but at the posterior end rapidly attenuated and shortly produced. 

 The valves are large, high, posteriorly truncate, and the gape reaches on the ventral 

 side to only about half the length of the shell. 



Locality. — Odium and Moraviatoor ; generally found boring in oyster shells. 



Formation. — Ootatoor group. 



