PANAMIC-PACIFIC PELECYPODA 27 



species of the genus attaining a length of nearly three inches; the group of 

 C. (Euclia) cassidijormis, also of large size; and the small C. (Aphera) 

 tessellata, these three species have closely related forms amongst the Carib- 

 bean Miocene fossils. Other interesting and striking cancellarids are: C. 

 (Ovilia) cumingiana-, C. (Narona) clavatida and the mitralike C. (Hert- 

 leinia) mitrijormis. Of special interest is the rare C. (Perplicaria) clarki 

 described by Maxwell Smith from Venado Beach, in the Canal Zone, the 

 only other known species in the subgenus is C. perplexa from the Caloosa- 

 hatchee Pliocene of Florida. Species of the Terebridae (about 35 species) 

 are plentiful throughout the province, some species have a great range, 

 others are more restricted; two of the largest species, T. robusta and T. 

 strigata, are common on mud flats. T. luctuosa, related to T. cinerea of the 

 Caribbean, is plentiful on sandy beaches; of a similar habitat is T. acicidata, 

 common in Peru. The family Olividae (with about 28 species) contains a 

 large number of interesting forms distributed amongst three main genera. 

 The largest and finest species of the family is the Oliva porphyria (the Pan- 

 ama Tent Olive), quite localized in its distribution but ranging from the 

 Gulf of California to Panama and the Galapagos Islands. Another large 

 Olive is Oliva incrassata (angulata) found on sand bars exposed at low 

 tide; this species has closely related forms in the Caribbean Miocene. Oliva 

 spicata (0. polpasta and several other names) is the commonest species 

 at most localities. Abundant at many places in Panama and Ecuador is 

 the small Oliva undatella, usually with a varied color pattern, and because 

 of its size, often referred to Olivella but with the shell and radular characters 

 of Oliva. Agaronia with two or more closely similar species is often seen 

 along beaches at low tide feeding on the smaller Olivellas. Olivella has many 

 species, many of which are local. Olivella (Lamprodoma) volutella is especi- 

 ally common in Panama on slimy mud flats and exhibits a wide range of 

 coloration from pure white to nearly black. Olivella {Pachy oliva) columel- 

 laris and 0. semistriata are typically open beach species and may occur in 

 countless numbers at favorable localities. The Conidae are represented by 

 about 33 species. Conus fergusoni and C. patricius are the largest forms, each 

 often reaching a length of four inches or more; both species have fossil rela- 

 tives in the Caribbean region. C. purpurascens is the commonest of all Pan- 

 amic cones and has the widest range, extending into northwestern Peru: in 

 the Caribbean, this species is represented by the similar C. ranunculus. C. 

 dalli is a relatively rare species, the only member of the C. textilis group and 

 probably a recent arrival from the Indo-Pacific region; it has no fossil rela- 

 tives in the American Tertiary. The turrids, because of their large number, 

 are the poorest known of all Panamic gastropods, and new species can be 

 expected in any dredge haul taken at new localities. The genus Polystira is 

 represented by two species, P. picta and P. oxytropis, both fairly common 

 from dredgings in waters of a few fathoms depth; both species have allied 

 forms as fossil in the Pacific and Caribbean zone. Characteristic of the 

 Panamic fauna are the dark-colored species of Crassipira found abundantly 



