20 BULLETIN 351_, U. S. DEPARTMENT OF AGEICULTUEE. 



the tenacious clay soil, already saturated with moisture, has kneaded 

 into it additional water through the travel of the bulls and heavily 

 burdened pack animals until in places it becomes a semifluid mass 

 resembhng thick orange-red paint, often of a depth reaching to a 

 horse's beUy. During the dry season, when they dry out on top 

 and crust over, these "baches" are even more treacherous than in 

 their semifluid state, for when a horse breaks tln^ough the crust he 

 is the more hable to get mired. Only horses bred to this kind of 

 travel know how to handle themselves under such trying conditions. 



For draft purposes in this back country the bull is almost exclu- 

 sively used. Most of the freighting across the island and into the 

 interior is even now, and on the best roads, done by bull carts, except 

 for a short Hne of railroad between Rio Piedras and Caguas. Very 

 recently the auto truck and auto stage have been tried in the cross- 

 the-island freight and passenger service, as well as along the coast, 

 and their use unquestionably will be extended. 



At the time of the American occupation there were 254 kilometers 

 (about 160 miles) of narrow-gauge railroad in operation in the coastal 

 portion of the island. At the present time (1912) it is possible, 

 thi'ough the connections estabhshed between the various sugar com- 

 panies' railroads and the original public-service road, almost to en- 

 circle the island by rail. 



THE FOREST. 



The forests of Porto Rico are now so fragmentary and so limited 

 in extent and have been so materially modified by the acts of man 

 during several centm-ies that they afford of themselves httle basis 

 for classification and description. Clearings, severe cuttings, and the 

 culling of the more desirable timbers were noted by the earliest trav- 

 elers. Then, too, many native species have been transplanted from 

 their natural haunts to others and many introduced species have 

 been brought in and spread over the island. It has consequently 

 been necessary to draw extensively on information from a num- 

 ber of sources and to study the various formations as they have been 

 described in their undisturbed natural state in whatever other part 

 of the Tropics they could be fomid. In this manner only could a 

 •groundwork be obtained for classifying and distributing according 

 to their proper relations the remnants of the once extensive Porto 

 Rican forests,^ 



1 In describing tlie fundamental features of the various formations the works of Schimper and of Broun 

 particularly have been freely di-avm on, and in reference to special featui-es those of Harshberger, of Fer- 

 now, and Taylor, and of Woodward (see Bibliography), not to mention the various historical worlis which 

 have contributed side lights on matters of general distribution. 



The work of defining the distribution of formations is a comparatively simple one, because of their close 

 relation to the distribution of rainfall, which latter has been carefully charted by the local Weather Bureau 



