OP SOUTIIEPX INDIA. 
19 
<1. Terebratula Bii’LiCATA, Soiocrhif, PI. IV, Pigs. 2 — 17 ; PI. V, Pigs. 1 — 3. 
1815. Ter. hipUcala, Sow., Min. Conoli., vol. i, p. 201, pi. 90 (non A/iomia Iqdicata, Brocchi). 
1852. „ „ apud Davidson, Brit. Cret. Briicli., p. 65. 
1808. „ „ „ SchlojnbacL, Benecke’s Gcogn. Palajont. Beitrajge, vol. i, p. 433 (cum syn). 
T. testa ovata sea elongate ocata, antice scepissirne suh-trnncata atque plus 
minusve dbstincte hiplicala, rariter fere slmpliciten msinuata ; valvis fere cequaliter 
converts, aut vulva urnbonali altera paulo convexiore atque luterallter in parte ante- 
riore plus minusve prof unde insinuala ; superficie aut glabra aut concentrice sub- 
sulcate striata; unibone tumido, obtuso, valde incurvo, foramine rotunduto atque 
moderate pal ulo et crasse marginato trunoato^ deltidio brevi, nonnuncpiuni brevissiino, 
modice lulo, siinpjUci, antice abruptc declivi. 
There arc few oilier species of Drachiopods ivhich have caused greater confu- 
sion and more controversies among Pahcontologists than this one, which represents 
a large group of the so-called biplicatc Tercbratulce. The various opinions of differ- 
ent authors have been recently most ahly discussed by the late Dr. Schlocnhach 
(1. cit.), and it is not necessary to repeat them here. 
I will only mention that from the examination of Broc chi’s type specimen by 
Stemann and Triger,* it appears clear, that Brocchi’s wama Anoniia hiplicata edxv- 
not he applied to the cretaceous species, originally descrilicd by Soivcrhy as Tere- 
bratula biplicata. The former is hclicvcd to he probably identical with Soiverby’s 
liassic T. intendata, hut as this identification cannot he ascertained with sufficient 
accuracy, and, moreover, as that species belongs to a different section of Terebratula , 
every objection against retaining Soivcrhy’s denomination for the cretaceous form is 
removed; and it appears most judicious to drop Brocchi’s name altogether. 
T. biplicata is easily recognised from its allies by the moderately tumid form of 
the shell and the strongly incurved beak, perforated by a foramen of moderate size. 
Beak ridges and area are never distinctly developed. The size of the full grown 
typical form (pi. iv, figs. 2 — 1, figs. 10—13) is generally moderate, between 30 and 
40 mm. long, 22 — 28 mm. wide, and 18 — 22 mm. thick; the greatest ividth being 
usually a little in front of the middle, and the greatest thickness at or very near 
the middle. The hiplication of the front and the lateral encroachment of the brachial, 
or hamial, valve ui)on the median insinuation of the neural valve is always trace- 
able, but the degree to which this extends is very variable. In some specimens 
(figs. 10 11) it is only slight, in others (and these are perfectly identical with the 
type), it is more distinct (figs. 4 and 13 j. The surface is usually smooth, very 
finely punctated and marked ndtli more or less distinct strim of growth. Barely 
also a fine radiating striation is to he observed in places. The loop is simple, 
and equals about one-third the length of the brachial valve. 
In connection with the stronger concentric ornamentation, I may notice the 
peculiar variety which Davidson describes under the name T. sulcfera of Morris, 
and which Schloenhach identifies with T. biplicata, Sow. As regards general 
* Bull. Soc., Geol., 1861-C2, vol. ik, p. IGO. 
