Prof. Dr. F. Roemer—On the Genus Caunopora. 343 
length of the shell, and widening to the front. The ventral valve 
is moderately convex, flattened, or slightly depressed from about 
its middle to the front. Beak moderately projecting and incurved. 
Surface of both valves faintly and closely radially striated; striz 
thread-like, and intersected by numerous concentric lines of growth. 
On the internal cast of the dorsal valve the central muscular scars 
are sharply defined (Pl. X. Fig. 18). 
This species occurs at Pontréan. In his paper (Congrés de Nantes, 
1876) M. de Tromelin mentions having found it in the Grés Armori- 
cain of Pontréan. 
It is probable that when the exterior characters of this species 
are better known, that it will be necessary to separate it from 
Lingula proper, although it will retain its place among the T'reten- 
terata. The details we have been able to add from the study of the 
French specimens of the four Armoricain species will materially 
add to what was previously known of their characters, and little by 
little we may be able to clear up their history. Zingula Salteri does 
not appear to have been noticed by M. Rouault. 
EXPLANATION OF PLATE X. 
Fic. 1 to 6. Dinobolus Brimonti, Rouault, sp. 5. Internal cast of ventral valve. 
5a. Interior of same valve, reproduced by means of gutta-percha. 
6. Internal cast of dorsal valve. 6a. Interior of valve, repro- 
duced by means of gutta percha. 
» 1. Lingula Lesueuri, Rouault, a large typical specimen. 
» Stoll. Lingula Hawkei, Rouault. 8. Exterior. 9, 10. Internal casts of 
ventral valve, to show muscular impressions, and flattened 
margin. 11. Internal cast of dorsal valve, showing muscular 
impressions, and flattened margin. 
5, 12 to 13. Lingula Salteri, Dav. 12. A perfect bivalve specimen. 12a. Show- 
ing the two valves in profile. 13. Internal cast of ventral 
valve, showing central muscular impressions. 
All the specimens are from the ‘‘ Grés Armoricain’’ of Pontréan in Brittany, and 
are in the Collection of M. Lebesconte of Rennes. 
Il.—Nore on toe Genus Cauworora, of Phillips. 
By Prof. Dr. Frrp. RormEr, 
of the University of Breslau; For. Memb. Geol. Soc. Lond. 
NDER the name of Caunopora placenta Prof. Phillips described 
a fossil which is very common in the Devonian Limestone of 
South Devon, and which Mr. Lonsdale had described before as 
Coscinopora placenta. It forms amorphous or spheroidal masses 
composed of thin concentric laminz, and perforated by small flexuous 
or vermiform tubuli. 
The genus has since become the subject of repeated discussion by 
various authors. All of them agreed in the conclusion that the 
texture of the main mass of the genus is very similar to that of 
Stromatopora concentrica, which is found associated with Caunopora 
in the same limestone. The difficulty was how to account for the 
flexuous vermiform tubuli, which perforate the main mass at irregular 
distances, and in various directions. The greater number of writers 
on the subject regarded the tubuli as canals by which the communi- 
cation between the different parts of the body was effected, or at 
