NOMENCLATURE OF THE SHELL OF A SESSILE CIRRIPEDE. 
ARCHETYPE SHELL. Fig. 1. 
Orifice of shell, surrounded by the sheath. Sheath formed by the ale (a—a) and by portions of the 
upper and inner surfaces of the parietes (p—p). 


WNIzSOY 
“yavdWo0g *ye[-0.1480y //f) if 
‘gredui0g *ye]-ouneg ~“\\\ 
quouyiedmoy [e193eT i 
n.B. In Balanus, and all known fossil genera, the Rostrum and Rostro-lateral compartments are confluent, 
and hence the Rostrum has the structure of Fig. 2. 
COMPARTMENTS. 
Fig. 3. 

Fig. 2. Compartment with two radii, serving, in fossil specimens, always as a Rostrum. 
Fig. 3 serves as a Lateral and Carino-lateral Compartment. Fig. 4 serves as a Carina. 
OPERCULAR VALVES. 
Fig. 5. Scurum (internal view). Fig. 6. Trrevm (internal view). 




4 APeX ..... 7 
(GZ ; : Articular Ridge ....4..2 
2 \\i-Articular Ridge Articular Farrow... 
Za f ees Furrow ScuraL Marein....: 
AE Cavity for the Lat. 
i, Depressor Muscle. 
--- Lea 


sy CARINAL MARGIN 
OccLuDENT MARGIN _... < 
Cavity for Adductor 
Muscle : 
Adductor Ridge ;Z 
5... Crests for Depressor 
Muscle. 
Basat Marcin 

Spur. 
Fig. 7. Trev (external view). 
Beaked Apex ....s 



