80 U.S. NATIONAL ]VIUSEUM BULLETIN 259 



Collections from sites located in loosely consolidated Cretaceous and 

 Cenozoic sediments of the coastal plain (Tenn., Ala., and Miss.), and 

 from Paleozoic rocks of the southern Ozark Plateau region (Okla. and 

 Ark.) and Ouachita Mountains (Ark. and Okla.) are almost exclusively 

 from seeps and shallow springs presumably fed by shallow ground 

 waters. The majority of collections (6 out of 9) from the central 

 Ozark Plateau region in Missouri, however, are from caves predom- 

 inately developed in lower Paleozoic limestones. 



Most of the collections of this subspecies have been made during 

 winter and spring months (collections available for all months except 

 July, Sept., and Nov.), and it would appear as if this form like other 

 interstitial species of Stygonedes (especially S. tenuis) is more common 

 on the surface during the spring than at any other time. With one 

 exception, ovigerous females have been obtained from seeps and small 

 springs during March, April, and May; the exceptional record being 

 the lectotype female which was collected from a well in October. 

 Eggs and embryos were counted from a sample of 24 ovigerous females 

 and the data is summarized statistically as follows: Size range = 

 4.00 mm-8.25 mm (Mean==5.84, S.D. = 1.10); range in number of 

 eggs=2-15 (Mean-=7.87, S.D.=2.83, C.V. = 35%). 



Remarks. — I have designated a 6.50 to 7.00 mm long, ovigerous 

 female as the lectotype of this subspecies. The original label read: 

 "Crangonyx alabamensis, co-type. Coll. by C. F. Baker from well, 

 Auburn, Ala. 10-18-'98." This specimen was further labelled as a 

 paratype in the U.S. National Museum collection. Except for this 

 single female, the remaining specunens of the type series were not 

 deposited in the National Museum collection and are believed to have 

 been lost. 



Hubricht (1943) pointed out the "remarkable closeness" of «S. ala- 

 bamensis to S. americanus but failed to synonymize the two species. 

 Critical comparison of the type series of these two forms, further 

 supported by study of material from numerous localities mtermediate 

 between the two type localities, have failed to reveal any significant 

 differences, however, and I consider these two species synonyms. 



All material referred to Synpleonia clantoni by Hubricht and Mackin 

 (1940) was reassigned to Synpleonia americana in a later paper by 

 Hubricht (1943). But my recent examination of all but two of the 

 collections reported in 1940 indicate that about one-half of this 

 material cannot be assigned to either S. clantoni or S. americana 

 {=S. alabamensis s. str. as presently understood). Samples from 

 Madison and Wayne Counties, Mo., are sufficiently distinct from S. 

 alabamensis and, as shown below, constitute a new species. This is 

 also true of a collection from Polk Co., Ark., which makes up another 

 separate species. Material collected from Pontotoc Co., Okla., is 



