1517 



Pulley, Thomas E. 1952. 



An illustrated check list of the marine mollusks of Texas. Tex. J. Sci 

 4: 167-199, 13 pi. 



This publication was not seen. - J.L.M. 



1518 



Pulley, Thomas E. 1953. 



A zoogeographic study based on the bivalves of the Gulf of Mexico. Ph.D. 

 dissertation, Harvard- Univ. (abstract in Ann. Rept. Am. Malacol. Un. , 1952: 

 2-3) . 



It is assumed that an abstract by the same author entitled: Distribution of 

 mollusks in the Gulf of Mexico. Am. Malacol. Un. Ann. Rept. 1952 (1953), 

 contains the gist of this dissertation. The abstract is summarized below. 

 - J.L.M. and M.W.S. 



1519 



Pulley, Thomas E. 1953. 



Distribution of mollusks in the Gulf of Mexico. Pacific Div. A.M.U.P., 5th 

 Ann. Meeting. In Am. Malacol. Un., Ann. Rept. 1952, 18th Ann. Meeting: 2-3. 



Study of identity and ranges of 238 species and subspecies in shallow water 

 in the Gulf of Mexico showed that most species were not scattered indiscrimi- 

 nately along the coastline, but were concentrated in a relatively few narrow 

 regions of faunal transition. These zones are also zones of temperature 

 transition, in which mean min winter temp or mean max summer temp changes by 

 8° to 12°F/100 miles. In regions of faunal uniformity, however, temp varies 

 about 1°F/100 miles. Where temp change is about 4° to 5°F/100 miles, ranges 

 of many species are terminated at scattered intermediate points between the 

 more pronounced faunal and temp discontinuities on either side. The following 

 faunal provinces were recognized: 1) Nova Scotian, south coast of Newfoundland 

 to Cape Cod; 2) Virginian, Cape Cod to Cape Hatteras; 3) Carolinian, Cape 

 Hatteras to Cape Canaveral; 4) South Florida, Cape Canaveral to Key West and 

 Cape Romano; 5) Southwest Florida, Cape Romano to Anclote Keys; 6) Northeast 

 Gulf, Anclote Keys to Mississippi River; 7) Northwest Gulf, Mississippi River 

 to Matagorda Island; 8) Texas Transitional, Matagorda Island to Cabo Rojo; 

 9) Mexican, Cabo Rojo to Cabo Catoche; 10) West Indian, West Indies, Central 

 and South America to Brazil; and 11) Offshore West Indian, 25 to 100 fathoms 

 in Caribbean Sea and Gulf of Mexico. Range limits determined by temp north of 

 Cape Hatteras must be caused by summer temps, south of Cape Hatteras by winter 

 temps. Adults have upper and lower temp limits for survival, but for most 

 species reproduction is limited to a narrower range. Where range limits are 

 determined by summer temp, northern range limits are in localities where temp 

 is not high enough for reproduction; southern range limits must be in regions 

 too warm for adult survival. Inability to reproduce at peak summer temp is 

 not important, because spawning can occur in spring or fall. The reverse is 

 true where range limits are determined by winter temps, so that north of 

 Cape Hatteras the northern limit is controlled by temps too low in summer for 

 reproduction, and the southern limit by temps too high in summer for adults, 

 and south of Cape Hatteras the northern limit is where it is too cold in 

 winter for adults, and the southern limit where it is not cold enough in 

 winter for reproduction. It is possible to predict with reasonable accuracy 

 the temp extremes of regions for which no data are available, if temp 

 requirements of species are known from their range limits elsewhere. This also 

 applies to late Tertiary or Quaternary horizons in which recent species were 

 present. The area from Cape Hatteras to Cape Henry is particularly depauperate 

 because the area has a sharp winter temp break, with an annual temp range of 

 50°F. Other factors also are important in determining distributional ranges. 

 - J.L.M. 



424 



