374 INFERIOR OOLITE AMMONITES. 
obviously suggests the name palmata for this species, palmate being the botanical 
term for a leaf of five or more narrow lobes united near the main stalk." 
Only one of the Sonninia suture-lines figured has any close resemblance to that 
of the present species. It belongs toa fossil of very distinct shape and ornamenta- 
tion, namely, Sonn. obtusiformis (Pl. LXXII, figs. 3—5) ; and the likeness is only 
superficial. A further study of that suture-line, with some new details obtained 
by further removal of test, is given in the same plate for comparison (Pl. XC, 
fig. 10). The homologous parts have been lettered to correspond with those of 
Sonn. palmata ; and it will be seen that, though both lobes are pentadactyloid, 
there are important differences between them. In Sonn. obtusiformis the lateral 
lobules, A and (, are bipartite; and they are more equally arranged each side of 
the terminal lobule. Thus the lobe may be said to be fairly balanced, although it 
cannot be described as symmetrical, because the terminal lobule is intra-axial, 
anisosceloid, and certainly not equicellate. Its inner lobule C, though somewhat 
abbreviated, has compensation in the strong offshoot c*; but, in palmata, O is small, 
and its bipartition is rudimentary. The principal difference, however, is in con- 
nection with the outer lobule, A: in obtusiformis there is no distinct shoot to 
correspond to a’ of palmata; the shoots apparently correspond only with a’ and a* 
of this species. Lastly, the outer interlobular cell is very much smaller in obtusi- 
formis than in palmata. Thus the two superior lateral lobes do not correspond in 
detail, and their differences may be stated by the following formule : 
S. palmata—a’*, a’, a’, B, C. 
S. obtusiformis—a’, a, B, c', c’. 
Both of these lobes may conveniently be compared with the papilioniform 
superior lateral lobe of S. papilionacea (Pl. XC, fig. 3), where the formula is— 
S. papilionacea—a’, a’, B, c', c’. 
One specimen of the present species was obtained in the summer of 1892, 
during the excavations at Sherborne in the Sandford-Lane quarry.” It came from 
strata in which Inoceras concavum and allies abound, and was about fifteen inches 
below the “Fossil Bed” (see ‘Quart. Journ. Geol. Soc.,’ vol. xlix, p. 493, 
Bed sila): 
This unique and most interesting specimen is figured in Pl. XC—fig. 7, side 
1 Since the above was written Prof. Blake has used the term “ palmate ” for the lobes of certain 
Lytocerata (‘‘ Classif. Ammonites,” ‘ Proc. Geol. Assoc.,’ vol. xiii, pt. 2, p. 37), but they are really 
tridactyloid. 
2 These excavations were undertaken by Mr. Hudleston, F.R.S., and myself to determine the 
position of the strata to which foreign authors had applied the term “ Sowerbyi-zone.”” A paper by 
myself on the result of these excavations and other investigations in the district was read before the 
Geological Society, June 7th, 1893 (Abstracts, No. 610). It was entitled “The Bajocian of the 
Sherborne District: its Relation to Subjacent and Superjacent Deposits.” 
