2(58 
THE GEOLOGIST. 
Fig. II. rrnihiciiif hmgi^pinus. From tlio orig-iiial spociincii of Sowcrby's P. 
Fleiningii ; West Lothian and collection of Dr. Fleming' 
15. . Interior of the ventral valve ; irom Capel Rig 
and collection of Mr. Armstrong:. 
Id. . Dorsal valve, fi-om the same locality. 
17. . From the Campsie main limestone ; collection 
of Mr. Young. 
IS. . A curious variety from Gare. 
19. . A variety in which the sinus has not been 
developed ; Prod, spinosus, Sow., from the original example, slightly 
restored, and collection of Dr. Fleming. 
20. aculeatits, Martin. From the Campsie main limestone. 
21. mesnlohus, Phillips. From the Glarat lime-works, Campsie ; 
collection of Mr. Young. The shell has also been recently found at 
Brockley, near Lesmahago, by Mr. J. Thomson. 
22. costatus. Sow. Fi-om Barrhead ; collection of Mr. Young. 
23. , Sow. From near Lesmahago ; collection of Dr. Slimon. 
24. , Sow. Dorsal valve, Barrhead. The interior of the 
dorsal valve has been recently found at Bi-ockley, by Mr. Thomson. 
25. ?. Undetermined sj^ecies. From Corrie Burn ; collection of 
Mr. Young. 
26. Youngianus, Dav., type. The usual condition of the species, 
from the same locality and collection ; in pi. v., fig. 7 shows the con- 
centric lines of gi'owth. 
27. — fmhriatus, Sow. From Lanarkshire. 
Plate IV. 
1. Productus seniircticulatus, Martin. From Castlecary ; collection of Mr. 
Thomson. 
2. . NelMeld, Lanarkshire. 
3. . Interior of the ventral valve. From Calder- 
side ; collection of Mr. Annstrong. 
4. . Interior of the dorsal valve. From Calder- 
side ; collection of Mr. Annstrong. A, occlusor ; B, divaricatora ; 
J, cardinal process. Fig. 4a, cardinal process seen from its upper 
siu-face. Fig. 4b, a smaller portion of the internal surface close to 
the margin, showing the spinose aisperities, M, wliich covers its sui-- 
face, as well as the orifices of the minute canals which traverse the 
shell, N. 
P. Scotica, Sow. From the original specimen 
in the collection of Dr. Fleming. Figs. 7 and 8 show the disposition 
of some of the ribs. 
6. , var. sulcatus, Sow. From Carluke parish. 
10. , var. Martini. From ironstone under the 
Campsie main Hmestone ; collection of Mr. Somerville. Fig. 10& 
shows how the ribs bifurcate upon the lateral portions of the valves. 
11. . From the same locality. 
12. , var. P. concinnus. From the same locality; 
and showing how the shell becomes sometimes fractured. 
13. ayra, d'Oi-bigny. From the Campsie main limestone (Bal- 
grochan Glen beds). A more correctly enlarged fragment of the 
shell surface will be seen in pi. v., fig. 5. 
11. carhonarivs, de Koninck. In the collection of the Geological 
Survey this specimen is labelled " North of Glasgow" (?), a very 
vague indication ; and it is possible that the specimen may be from 
some other district of the Scottish Carboniferous series. 
15. undatuS) Defrance. From the Campsie main limestone. 
