90 HYDKOGEAPHIC REPORTS. 
I would recommend the selection of some point between Suchii 
and the mouth of the Jaltepec as a terminus, unless Other than 
hydrographic reasons forbid it. 
The extensive reconnaissances of the country between Boca del 
Monte and Tesistepec by means of the tributaries of the Coatza- 
coalcos, which you marked out in your instructions for the hy- 
drographic party, have not been made, owing to the character of 
the country upon the river banks, covered as it is by an impen- 
etrable jungle. It was found impossible to acquire any useful 
information of the topography of that region by exploring the 
different streams, or in any other manner, except by following 
the roads leading from the several ferries to the towns between 
Mina-titlan and Acayucam. This portion had already been ex- 
amined, and nothing could have been gained by the proposed 
reconnaissance. Subsequently, as you know, lines were run 
through this whole extent by the railroad parties, and all the 
desired information obtained. The same considerations pre- 
vented my ascertaining the limits of overflow on either side. 
In compliance with your instructions, attention has been paid 
to the natural productions and geology of the banks of the river, 
and I have already forwarded to you a report upon the first by 
Passed Midshipman John McL. Murphy, of the U. S. Navy ; 
and another, upon the second, by Mr. Walter W. de Lacy. 
The bar of the Coatzacoalcos River has been examined to de- 
termine its nature, the practicability of deepening it, and to test 
Leigh's chart, according to your instructions. As I have else- 
where remarked no changes have occurred since Lieut. Leigh's 
survey in 1848. 
My efforts to ascertain the precise character of its formation 
were not entirely successful, inasmuch as 1 failed to get a 
specimen of the bar itself; but I convinced myself that it is of 
limestone, mixed with indurated clay in some parts, and cov- 
ered with a light layer of coarse, loose sand. The SteMwagon 
lead of course would bring up nothing but the sand, but the 
presence of the rocky foundation was satisfactorily proved by 
probing the bottom with a lortg pole, the heavy end being shod 
with a sharp iron pike. As well as could be judged with these 
means of investigation, the layer of sand was, on an average, 
