385 
migrated from the north,* others migrated from the south. 
This is especially remarkable among the Brachiopoda,+ whose 
powers of locomotion would be small; I can give a few inter- 
esting examples of this. 
Aulacothyris carinata (Lamarck) apparently migrated to the 
Cotteswolds from the south. It isa plentiful species in Dorset, 
is found less frequently in Somerset (Castle Cary district), and 
seldom in the Cotteswolds. 
Zeilleria emargainata (Sow.) follows exactly the same lines. 
Terebratula spheroidalis (Sow.) began in the Humphriesian- 
um-zone, and continued into the Parkinsoni-zone and the Fuller’s 
Earth; it is found plentifully, and of large size, in South Dorset, 
not so large in North Dorset, smaller still in Somerset (Castle 
Cary district), and is not found at all in the Cotteswolds. 
Terebratula Stephani (Dav.), Terebratula Phillipsit (Morris), 
Terebratula decipiens (KE. Desl.) are found in the Dorset-Somerset 
area, but not in the Cotteswolds. 
Rynchonella subtetrahedra (Dav.) is found in all the areas; 
but Rhynchonella plicatella (Sow.) and Acanthothyris panacanthina 
only in the former. 
Zeilleria Hughesi (Walker) migrated from the Cotteswolds. 
Tt is found plentifully in the North Cotteswolds, less so in the 
South Cotteswolds, and rarely in the Castle Cary district. 
Terebratula globata (Sow.) is also a migrant from the 
Cotteswolds. It is found plentifully and in great variety in 
that district ; scarce in the Castle Cary district, and extremely 
= Where did the ancestors of these species live during the period of the 
Humphriesianum-zone? It was probable that a northward extension of the 
Cotteswold Inferior Oolite—an extension towards Warwick—at this time 
received the deposit of this period. 
That the Jurassic strata once extended away into the Irish Sea, via the 
Mersey, is proved by the Liassic outliers near Burton-on-Trent and Market 
Drayton. Possibly all this area was once covered by Inferior Oolite. 
+ It would seem as if Ammonites were still prevented from invading 
the Cotteswold area, either on account of the existence (beneath the sea) of 
the barriers mentioned, or on account of the shallowness of the water. 
¢ A form called Phillipsiana is found at Cleeve ; I fancy its horizon is 
lower. 
