BRACHIOPODA. 
335 
Genus ETHERIDGINA, (Ehlert. 1887. 
1876. Productus, Etheridge, jr. Quart. Journ. Geol. Society, vol. xxxii, p. 454, pi. xxiv, figs. 1-14; 
pi. xxv, figs. 15-24. 
1878. Productus, Etheridge, jr. Quart. Journ. Geol. Society, vol. xxxiv, p. 498. 
1880. Productus, Davidson. Monogr. British Carb. Brach. Suppl., p. 303, pi. xxxv, figs. 4-13. 
1887. Etheridgina, CEhlert. In Fischer’s Manuel de Conchyliologie ; Brachiopodes, p. 1278. 
Diagnosis. “ Shell of very small size, nearly as broad as long, attached to 
foreign bodies by the spines of the ventral valve; cardinal line straight, nearly 
equaling the greatest width of the shell; pallial outline semicircular; ventral 
valve with a small, entire [?] beak; surface ornamented by concentric flexuous 
plications, bearing a few scattered spines; cardinal process quadrifid.”— 
(Ehlert, ut. cit. 
Type, Productus compledens, Etheridge, Jr. 
Figs. 31-37. Productus ( Etheridgina) compledens, Etheridge. 
After Etheridge. 
Observations. This shell was admirably described by Mr. Etheridge in his 
paper on “ An Adherent Form of Productus ” (1876) and presents the interest¬ 
ing combination of distinctive productoid characters (absence of cardinal area, 
hinge, etc.), with a mode of growth characterizing the genus Strophalosia. 
The very small shells of this genus, which is thus far represented by the type 
species only, have been found adhering to crinoid columns and fragments of 
bryozoa; that is, to surfaces of little expansion; hence the creeping spines 
appear to effect an attachment by encircling or hugging their host. This ap¬ 
pearance is somewhat deceptive; the surface of the pedicle-valve is itself 
adherent, and the mode of growth of both shell and spines the same as that 
already observed in some of the small species of Strophalosia (S . radicans, 
