Xviii GEOGRAPHIC DISTRIBUTION. 



C (P-) grandis, p. 154. C sauridens, p. 171. 



C. ampuUaceus, p. 158. C. amiantis, p. 174. 



C. exiguus, p. 159. C rastridens, p. 174. 



C. obesus, p. 159. C. curtus, p. 175. 



*C. tumidosus, p. 160. C. acus, p. 191. 



C. curcurbita, p. 161. C dominguensis, p. 191. 



Panamic province — Ecuador to Loicer California. 



Fourteen species of Dentalium and six of Cadulus are known, five 

 of the former genus, four of the latter having occurred only in depths 

 greater than 300 fms. The rest are shore species, all of them prob- 

 ably to be found living within the 25 fathom line. D. tesseragonum, 

 quadrangulare, semipolitum, sectum, inmimerabile and brevicornu, 

 and Cadulus perpusillus and panamensis have their nearest allies in 

 the Antillean Tertiary and recent faunas ; some of them being at 

 most only varietally distinct from their AVest Indian counterparts. 



D. cequatoriwn and dalli and Cadulus albicomatus and striatus are 

 ■essentially West American types, having no near allies in Antillean 

 or Oriental seas. In general, the deep water Panamic Scajihopods 

 belong mainly to what seem to be endemic West American groups 

 -of species, while the shore or shallow water species are very inti- 

 mately related to Antillean forms. 



Dentalium oerstedi D. inversum. 



D. agassizi, 322-1,020 fms. D. splendidum. 



D. tesseragonum. D. sectum. 



D. quadrangulare. D. sequatorium, 401 fms. 



D. fisheri. D. dalli, 660 fms. 



D. megathyris, 812-2,282 fms. D. innumerabile. 



D. semipolitum. D. brevicornu, 634-995 fms. 



Cadulus striatus, 322 fms. C. californicus, 1,270 fms. 



C. albicomatus, 401-1,672 fms. C. perpusillus, p. 190. 

 ■C. platystoma, 401 fms. C panamensis, p. 191. 



Key to Panamic species of Dentalium. 



a. Shell square at apex, keeled on dorsal, ventral and lateral faces. 

 b. Smooth and rounded toward aperture ; length 20 mill., 

 8 times the diam., tesseragonum, p. 34. 



b'. Interstices striated throughout. 



c. Length 20 mill., 5} times the diam., 



quadrangulare, p. 35. 



