BRACHIOPODA. 
103 
in palaeozoic faunas in which the accessory lamellae attain so high a develop¬ 
ment. As already observed, Bittner has detected a number of such 
double-spired forms in the Alpine Trias, over all of which he extends the 
generic term Athvris (or Spirigera), though he has introduced for them a 
number of subordinate names based upon slight differences of structure, as 
follows; 
Pexidella ; smooth forms with thickened shells, and loop of inconspicuous 
size. 
Diplospirella ; smooth forms without shell-thickening and with prominent 
loop. 
Euractinella ; cinctured forms with slightly developed area and broad ribs 
separated by deep, narrow furrows. 
Anisactinella ; forms with alternating ribs, area and elevated deltidium. 
The duplication of the spirals has also been observed in other Triassic genera, 
notably Koninckina, Suess, and Amphiclina, Laube shells differing from 
Kayseria and its Triassic allies in so many other points of structure that a close 
phyletic connection between them seems highly improbable. 
Genus RETZIA, King. 1850. 
PRATE L. 
1845. Terehratula, db Vernbdil. Bull, de la Soc. geol. de France, second sei’., vol. xi, p. 471, pi. xiv, 
figs. 10 a-d. 
1850. Retzia, King. Monogr. Pei'iiiiaii Foss. England, p. 137. 
1854. Retzia, Davidson. Introd. British Fossil Brachiopoda, p. 88, pi. vi, fig. 77. 
1886. Retzia, CEhlbrt. Annales Sci. Geol., vol xix. No. 1, p. 24, pi. xi, figs. 11-19. 
“ A Spiriferidia; in general oval longitudinally; ribbed or striated; with 
long punctures. Large valve foraminated at or near the apex of the umbone; 
with a triangular area, and a closed fissure. Type Terehratula Adrieni, De Ver- 
neuil.” (King, Monogr. of the Permian Fossils of England, p. 137.) 
The term Retzia has come into general use as a designation for palaeozoic 
brachiopods which have an elongate-ovate form and radially plicated exterior. 
*See Laobb, Die Fauna der Schichten von St. Cassian, Zweit. Abtheil., p. 28. 1865. 
Beecher, American Journal of Science, vol. xl, p. 211, pi. ii. 1890. 
