Cretaceous Gastroidoda, and Pelecypoda from Zululand. 41 
well marked, as also is the elongate insignificant escutcheon which 
is of such narrow dimensions (= about -|- a millimetre). The valves 
are exceedingly robust and thick, with a wide arching and con- 
sequently of rather shallow capacity, whilst their general facies 
would allow of a comparison with a form like Trigonia carinata of 
Agassiz which has been recorded from Lower Cretaceous (Neocomian 
to Aptian) rocks of Britain, Switzerland, &c. 
Agassiz's shell is, however, of much greater convexity, its sculpture 
on the posterior region is much more complicated, including a system 
of radial ornamentation, whilst the escutcheon area is wider and 
more cordiform ; the pallial costae are angulate and thin, less curved, 
more oblique, extending right up to the outer anterior margin in a 
series of nearly horizontal lines produced by an obtuse angulation 
occurring about 10 mm. from the border ; in the ventral direction 
the costse are also sometimes broken and irregular. 
Several species of Trigonia have been recorded from the Cretaceous 
rocks of India and Africa, but so far as present inquiries have gone 
none exhibit the details of the shell from Zululand, although mention 
may be made of T. tatei of Holub and Neumayr (— T. cassiope of 
Tate non Orbigny), described and figured from the Uitenhage deposits 
of South Africa which belongs to Agassiz's group of the " Costatge." 
The Uitenhage shell is, nevertheless, more quadrate in contour, the 
pallial costse are more deeply curved and less obliquely disposed, 
whilst the posterior region bears a well-ornamented series of radial 
ribs. The costate Trigonise, which belong more particularly to 
Jurassic rocks, are invariably furnished with a highly decorative 
posterior surface, but in the present shell a strongly costate anterior 
region is observed in association with a smooth posterior surface. 
It is among the groups Scaphoidese and Clavellatae that the smooth 
posterior surfaces are to be found, but then they are accompanied by 
variously arranged nodulations which ornament the anterior division 
of the valves. 
Such facts as these seem to suggest that the shell from Zulu- 
land may represent an intermediate form coming between the 
" Clavellatse " and " Costatae." 
I have much pleasure in naming this shell after Dr. Blanckenhorn, 
who has done some important work on the Cretaceous palaeontology 
of Syria and Egypt. 
Locality. — North end of False Bay. . 
* Denksithrift. K. Ahad. Wiss., 1882, vol. 44, pi. 2, fig. 3, p. 275. 
