302 C. T. Trechmann — Cretaceous Mollusca 



apparently by absorption or erosion. In one of my specimens tbere 

 is a small Anomia attached to the surface near the inner lip which 

 suggests that the shell may have lain mouth upwards in the sand. 



Locality. — In the Upper AVaimakariri Gorge there is a bed about 

 3 feet thick not far above the local base of the Cretaceous almost 

 made up of thousands of these shells, some perfect and others broken. 

 They show considerable variation in the degree of growth of the 

 shelly callosity and the extension of the lip. The only other fossil 

 that I found associated with them in this locality were a few valves 

 of Trigonia Hanetiana, d'Orb. At Selwyn Rapids the shell is less 

 plentiful, and is better preserved in the harder parts of the rock, but is 

 in all respects similar to the specimens at Waimakariri. 



It seems, as one might expect in so specialized a shell, to have 

 a restricted vertical range, and may be regarded as a characteristic 

 fossil of the Upper Senonian. 



This form is apparently quite absent from the higher Wangaloa 

 Beds, where it is replaced by a beautiful shell recently described by 

 Professor Marshall as Pugnellus australis. 



Pugnellus Maushalli, sp. nov. (PI. XIX, Figs. 1-4.) 



The shell consists of six whorls, the last one large and inflated. 

 Above the middle of each whorl there is a row of blunt nodes, and 

 below these on the last whorl a row of smaller and less prominent 

 nodes which in some specimens coalesce into a raised ridge. The 

 sutures are shallow. The outer layer of the shell bears very fine 

 concentric raised lines. 



The lip is not developed to the exaggerated extent it is in some 

 forms of Pugnellus. The outer lip is extended and swollen, and ends 

 in a rounded claw-like protuberance which is very easily broken off. 

 Anteriorly there is a channel, but the shell is not drawn out. 

 Posteriorly there is a wide semicircular channel formed by the 

 swollen lip of the shell. The callosity of the inner lip reaches 

 in most specimens to the top of the third whorl from the mouth, and 

 in one or two examples it extends above this nearly to the apex. It 

 is a shell of moderate size, the height being about 26mm. 



This shell was formerly erroneously supposed to be a Struthiolaria 

 or Pelicaria, and a specimen was recently identified as such by 

 Mr. Suter, and Prof. Marshall 1 remarks that it is the first occurrence 

 of the essentially Tertiary form Struthiolaria in Cretaceous rocks. 



I obtained, however, nine or ten perfect examples with entire lips 

 and can definitely say that it is a true Pugnellus. It often happens 

 that the specimen is immature or the lip is missing when the 

 sculpture on the earlier whorls of the shell certainly recalls that on 

 the recent Pelicaria. However, in no Struthiolaria that I have seen 

 does the labial callosity extend to beyond the lower half of the 

 penultimate whorl. The same remark applies to Pelicaria, which 

 has in addition a thin smooth shelly deposit covering the back of the 

 lust and penultimate whorl. Neither Struthiolaria nor Pelicaria 

 has the thickened and swollen outer lip characteristic of Pugnellus 

 which is so conspicuous in the present shell. 



1 Trans. N.Z. Inst., vol. xlviii, p. 118, 1915. 



