General Discussion 65 



11. Transformation structures. Often at transformation it is extremely 

 difficult to determine the Hylids or tree frogs. They are frequently each of 

 them green at this stage. The taking on of their color pattern from trans- 

 formation onward may often give a clue to relationship. For example, on this 

 basis one might be tempted to place Hyla cinerea, Hyla andersonii, and 

 Hyla gratiosa together. 



HYPOTHESES 



This topic is dangerous. It might give a fine chance for pleasurable 

 writing. One might develop it with increasing confidence as one grew older. 

 None of the following suggestions do we urge and their tentative characters 

 merely show some habits of mind which have pervaded previous attempts 

 at the relationships, distribution and origin of American biota. I hope no one 

 will expend most of their energy on this part of our paper and tilt any hypothe- 

 sis hard until he or she has labored industriously on the forms in question. 



Some of these fancies are: i. Is it worthy of consideration that those 

 forms of Europe which Boulenger places below 4,200 feet elevation (namely, 

 Rana agilis, Rana esculenta, Bufo calamita, Hyla arborea, Pelobates fuscus, 

 and possibly others) might have counterparts in our Atlantic coast region 

 in Rana sylvatica, Rana virgatipes, Bufo fowleri, Hyla andersonii, Scaphiopus 

 holbrookii, etc.? Three of them are yet unrecorded from Okefinokee region 

 and one not common and one on the outside of the swamp. 



2. Is the Okefinokee region near the center of distribution of the forms 

 of the United States of America with its eight Hylids (2 Pseudacris, i Acris, 

 5 Hyla), and three more possible Hylids, (2 Pseudacris and Hyla andersonii) 

 or six Rana species or two diverse Bufos or i Scaphiopus and i Gastrophryne — 

 18 species with 4 or 5 more possible, or 22 or 23 in all? For example, would it 

 be safe to say the region of the south eastern United States is the center of 

 the single laying Hylids, namely Hyla squirella, Hyla gratiosa, Acris gryllus, 

 Pseudacris ocularis, and that from one of these came the lone northern species, 

 Hyla crucifer? Or from a Rana grylio-\ike form came the more widespread 

 northern R. catesbeiana, R. virgatipes, and Rana septentrionalis, all very 

 aquatic? Or from Rana sphenocephala came the widespread northern Rana 

 pipiens, or from Ra7ia aesopus, the more widespread northern Rana areolata? 



3. Or are some of the Okefinokee species so hmited in distribution 

 (South Carolina to Louisiana, or less) to be merely Sabalian representatives 

 of northern species? Shall we call the aberrant Pseudacris ocularis a Sabalian 

 offshoot from the northern Hyla crucifer, Rana grylio a bigger Rana virga- 

 tipes, Rana heckscheri a bigger Rana clamitans, Hyla gratiosa a bigger Hyla 

 ciner'ea? 



4. Did most of our southeastern forms come from the southwestern or 

 Mexican center, another favorite method of explanation? Did Bufo quercicus 

 come from Bufo compactilis, Bufo cognatus or some southwestern form, or 

 Bufo terrestris from Bufo valliceps'^ Is Hyla squirella of the Hyla eximia, 

 Hyla regilla group? Or are Hyla versicolor, Hyla avivoca, Hyla phaeocrypta, 

 Hyla femoralis from a Hyla arenicolor center? Is it reasonable to hold that 



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