NO. 1177. NORTH AMERICAN LEPTONACEA— BALL. 889 



dorsal side of the animal and as long as its sliell, while the foot is 

 pointed in front and ])roduced into a cylindrical, extremely extensile 

 ''heel" behind. The byssal gland is situated at the extreme conical 

 end of this organ, which can be moved about like a finger and emits 

 when needed a single byssal thread. When fullj^ extended it may 

 reach twice the length of the shell. It will be seen at once on com- 

 paring Stimpson's figures (here first published) with Deshayes's figure 

 of the type species of Bornia^ that the two are quite ditterent animals. 

 For this reason I have separated Stimpson's species under the name of 

 Ccratobornia. The produced hood of Bornia is apparently lacking. 

 (See Plate LXXXVIII, figs. 10, 11, 13.) 



BORNIA PULCHRA Philippi. 

 B. 10. KelUa pnlchra Philippi, Zeitschr. fiir Mai., V, 1848, \i. 149 



BORNIA RETIFERA Dall. 



Bornia retifera, new species. 



(Plate LXXXVII, fig. 2.) 



B, 12. Shell thin, white, moderately convex, rounded, trigonal, nearly 

 equilateral; beaks distinct, not high ; surface polished, with faint incre- 

 n)eutal lines and minute close punctations whose interspaces give the 

 effect of a fine netting; hinge normal, delicate; adductor scars rounded, 

 high up; posterior basal margin very .slightly crenulate. Lon. 12, alt. 

 9, diam. 4 mm. 



One left valve dredged by the U. S. Fish Commission at station 2900, 

 in 13 fathoms, off Santa Kosa Island, California. 



The microscopic sculpture distinctly separates this from any other 

 American species. 



KELLIA (SUBORBICULARIS var.) GOULDII Thomson. 



Montacuta gouldii Thomson, Am. Jouru. Conch., Ill, 1867, p. 33, pi. i, fig. 1.5. 



A. 15. An examination of Thomson's types shows that his species is 

 identical with the shell hitherto identified as Kellia suborhicuJaris, from 

 southern New England. It is also j)robably Lepton fabagella Conrad,^ 

 but Conrad's unique type is lost, and his description and figures insufii- 

 cieut for iwsitive identification. All the specimens of this form hitherto 

 Ibund on the New England coast are notably smaller and more delicate 

 thq,n adult British examples, and it may prove distinct. On the other 

 hand Pacific coast specimens (B. 14), in size and all other features, agree 

 well with the European shells. 



' Fischer, Manual, p. 1026, tig. 772, where it is called B. complanata erroneously. 

 2 Am. Mar. Couch., 1831. 



