STtTDIES m FORAMINIFEEA 



161 



Glohorotalia lehneri Cushman and Jarvis, together 

 with Glohorotalia spinulosa Cushman and Glohorotalia 

 spinuloinflata (Bandy), belongs to a group of Glohoro- 

 talia species that does not develop a distinct preference 

 for one coUing direction. This is rather exceptional, 

 because it is known that most Glohorotalia species 

 from the upper Paleocene to the Recent, especially 

 the more highly developed angidar and keeled forms, 

 do develop a distinct preference for either sinistral or 

 dextral coiling (BoUi, 1950, 1957a). 



A number of specimens of Glohorotalia centralis 

 Cushman and Bermudez, from the Globigerapsis kugleri 

 zone to the Glohorotalia cocoaensis zone, were checked 

 for the direction of coiling. During the early stage of 

 evolution in the Globigerapsis kugleri and Glohorotalia 

 lehneri zones specimens coiled at random, but a 60-80 

 percent preference for sinistral coiling was found in 

 the Porticulasphaera mexicana, Globigerapsis semi- 

 involuta and Glohorotalia cocoaensis zones. The pref- 

 erence for sinistral coiling in Glohorotalia cocoaensis 

 Cushman, a species thought to have developed from 

 Glohorotalia centralis, is probably over 80 percent. 



Forty-foiu' planktonic Foraminifera species and sub- 

 species belonging to eleven genera are recorded though 

 full descriptions are given only for the six new species. 

 Synonymy lists are restricted to the original description 

 and to Uterature concerning the Caribbean, the Gulf 

 Coast region, Central America and northern South 

 America. The species of the genera Hantkenina, 

 Crihrohantkenina, and Chiloguemhelina have previously 

 been described in detail and are left out of this paper. 



The range of many of the species is not restricted to 



the Navet and San Fernando formations. Several 

 originate in the Paleocene-lower Eocene Lizard Springs 

 formation while some continue into the Ohgocene-Mio- 

 cene Cipero formation. However, the complete range 

 as observed in Trinidad is given in the notes on each 

 species. 



For the description and stratigraphic distribution of 

 the Chiloguembelmae and related genera in the Navet 

 and San Fernando formations reference is made to 

 Beckmann (1957). 



Bronnimann (1950a,b) described the species of the 

 genera Hantkenina and Crihrohantkenina fully but dis- 

 cussed their stratigi-aphic distribution only in a general- 

 ized way. Within the new zonation the range of some 

 of the better linown species was found to be as follows: 



Hantkenina aragonensis Nuttall, a species closely re- 

 lated to H. mexicana Cushman and H. lehneri Cushman 

 and Jarvis, is restricted to the zone of the same name. 

 A probable descendant of Hantkenina aragonensis is 

 H. dumhlei Weinzierl and Applin which succeeds it in 

 the Globigerapsis kugleri zone. Hantkeninae of the 

 longispina-alabamensis type follow H. dumhlei in the 

 higher zones of the Navet formation. In the San Fer- 

 nando formation the Hantkeninae have a tendency to 

 become smaller. This could either be an indication of 

 a gerontic stage or be due to less favorable ecologic 

 conditions. Hantkenina primitiva Cushman and Jarvis, 

 originating in the uppermost Navet, is the most abun- 

 dant Hantkenina species in the San Fernando formation 

 where it occurs with Crihrohantkenina bermudezi 

 (Thahnann) . 



Systematic Descriptions 



Family Hantkeninidae Cushman, 1927 



Subfamily Hastigeriainae BoUi, Loeblich, and 



Tappan, 1957 



Genus Hastigerina Thomson 



Hastigerina micra (Cole) 



Plate 35, Figures la-2b 



Nonion micrus Cole, Bull. Amer. Paleontol., vol. 14, No. 51, 



p. 22, pi. 5, fig. 12, 1927. 

 Globigerinella micra (Cole), Glaessner, Publ. Lab. Paleontol. 



Moscow Univ., vol. 1, fasc. 1, p. 30, pi. 1, figs. 4a-b, 1937. 



Stratigraphic range: Hantkenina aragonensis zone, 

 Navet formation to Glohorotalia cocoaensis zone, San 

 Fernando formation. 



Locality: Figured hypotypes (USNM P5698a,b) 

 from the Porticulasphaera mexicana zone, Navet forma- 

 tion; block in the upper Oligocene-lower Miocene 

 Nariva formation, in cutting west of tank 127, north 

 of The Avenue and 850 feet west of its junction with 

 Bon Accord Road, Pointe-a-Pien-e. Sample Hg 8581 

 (TTOC 215782) . The block is no longer existant. 



Remarks: With the exception of the Glohorotalia 

 palmerae zone, Hastigerina micra (Cole) occurs through- 



out the Navet and San Fernando formations but does 

 not continue into the Oligocene-Miocene Cipero forma- 

 tion. Glaessner (1937) changed the generic status of 

 this species to Globigerinella which is now regarded as a 

 junior synonym of Hastigerina (BoUi, Loeblich, and 

 Tappan, 1957, p. 29). 



Genus Clavigerinella BoUi, Loeblich, and Tappan, 1957 

 ClaTigerinella akersi BoUi, Loeblich, and Tappan 



Plate 35, Figure 4 



Clavigerinella akersi Bolli, Loeblich, and Tappan, U. S. Nat. 



Mus. BuU. 215, p. 30, pi. 3, figs. 5a-b, 1957. 

 Hastigerinella eocanica Nuttall, Cushman and Renz, Cushman 



Lab. Foram. Res., Spec. Publ. 24, p. 38, pi. 7, fig. 17, 1948.— 



Weiss, Micropaleontology, vol. 1, No. 4, p. 309, pi. 2, figs. 



11, 13, 1955. 



Stratigraphic range: Hantkenina aragonensis zone 

 to Globigerapsis kugleri zone, Navet formation. 



Locality: Figured topotype (USNM P5699) from 

 the Hantkenina aragonensis zone, Navet formation; in 

 small ravine between mileposts 12 K and 12 K of the 

 Brasso-Tamana Road and the Navet River, Central 

 Range (see text-fig. 25). Sample HGK 8820 (TTOC 

 177760). 



