of the Lower Malm of Aargau. 301 
T. constricta, Héusl. T. globigerinoides, sp. nov. 
T. coronata, Brady (var.). T. helveto-jurassica, Hdusl. 
T., squamata, J. § P. T. vesiculata, Uhl. 
T. inflata, Mont. T. Reussi, Uhl. 
1. Zrochammina constricta, Hiiusl. 
2. Trochammina coronaia, Brady*. 
The forms which in the first paper I mentioned as probably 
belonging to 7. coronata may be a variety of this species ; 
but the minute size of 0°3 millim. diam., and the very thin, 
almost hyaline test are different, while the mode of growth is 
nearly alike. It is very rare; and as almost all the Jurassic 
arenaceous varieties are much smaller than their recent re- 
presentatives, they may be regarded as produced by unfavour- 
able conditions of life. 
3. Trochammina squamata, J. & P. 
Shell free, rotaline, composed of convolutions forming a regu- 
lar conical spiral, resembling Valvulina triangularis. Cham- 
bers regularly increasing in size, more than three in one whorl. 
Upper surface conical, trochoid ; inferior almost flat, concave, 
or slightly umbilicated. ‘Test thin, fragile, subtransparent ; 
cement colourless or ochreous. Surface rough. Diam. 0-4 
millim.. 
Typical specimens are very rare in the Amm.-transversarius 
beds; they differ but little from the descriptions given by 
Jones and Parker, Carpenter, Karrer, &c. 
4, Trochammina inflata, Mont. (Pl. XV. figs. 5-7.) 
Test rotaline, inflated, thin, composed of few convolutions, 
of which only the last is visible from the lower side. Peri- 
pheral margin rounded; umbilicus excavated. Segments 
large, regularly increasing in size. Larliest chambers often 
irregularly arranged, sometimes corroded ; last chamber oc- 
casionally very large. Colour brown. Surface rough. Diam. 
0°5 millim. 
Many specimens agree fully with recent forms, as described 
by Williamsony. 
The Jurassic 7. inflata is very variable, passing from 7. 
squamata into T. globigerinoides. The sutural lines of the 
oldest part are often invisible from a partial corrosion of the 
primary chambers. 
* Brady, “‘ Notes on some of the Reticularian Rhizopoda of the ‘ Chal- 
lenger’ Expedition,” Micr. Journ. vol. xix. p. 39, pl. v. fig. 15. 
+ Williamson, Ree. For. Gt. Brit. p. 50, pl. iv. figs. 93, 94. 
