Bulletin 30 422 



Phos veraguensis representing Phos Moorei ; Malea ringens re- 

 sembling M. camura ; Neverita glauca, close to N. ?iereidis ; 

 Scapharca grandis almost identical with .S. patricia ; Tellina 

 (Seissula) delicatula very like T. cercadica ; Sanguinolaria (Psam- 

 motella) operculaia resembling .S. Smithwoodwardi ; Miltha 

 childreni living in the Gulf of California, related to M. Smith- 

 woodwardi. The Oriental Bursa bufonia is allied to B. bufoni- 

 opsis and Cyprcsa (Pustularia) nucleus, also Oriental, represents 

 C. Gabbiana in the fossil fauna. A singular example of the 

 Pacific element in our faunas is furnished by the two Ostreas, O. 

 hailensis and O. megodon both also at Bowden, and forms identical 

 or very closely related are found on Cerros Island off the Cali- 

 fornian coast. Finally the marked resemblance of Costellaria 

 cadaverosa from the Philippines to C. Bullennewtoni may be 

 noted. 



The Evidence of the Areas. — An argument favoring the very 

 considerable antiquity of the horizons studied is the undifferenti- 

 ated character of the Areas. Not, however, earlier than Oligo- 

 cene because of the presence of so man}^ Scapharcas of the short, 

 erect, highly specialized type. Many of the species show charac- 

 ters of more than one section and appear to have developed be- 

 fore the latter became defined and crystallized. They show 

 mixed sectional features. For example, .S. hispaniolana is a 

 Cuncarca wi + h the cardinal area of Scapharca still remaining. 

 The related species S. cor-cupidonis and 6\ riocanensis also have 

 the cardinal area of Scapharca with other characters of Cuncarca, 

 while C. Willardausteni is not so highly specialized as modern 

 members of the group. S. Arthurpennelli is an Argina external- 

 ly, but vacillates between the cardinal area of Argina and Scaph- 

 arca and the teeth are intermediate. In brief our fossil Areas 

 apparently lived before the modern sections were definitely 

 evolved. 



Species in common with Bowden.— Qi the four hundred and 

 fifty-one species discussed in the systematic part of this report 

 one hundred and twelve are known to occur at Bowden. That is, 

 slightly less than a quarter of the Santo Domingo species were 



