No. 1. — (Letter No. 1.) To C. P. Patterson, Superintendent Coast 

 Survey, Washinyton, D. C, from Alexander Agassiz, on the 

 Dredging Operations of tJie United States Coast Survey, Steamer 

 " Blake" during parts of January and February, 1878. 



Since I joined the ship at Havana, during the last part of December, 

 1877, not only have our operations been greatly retarded by continued 

 bad weather, but also by the unfortunate grounding of the " Blake " 

 at Bahia Honda while in charge of a Spanish pilot. Nearly three weeks 

 were lost before the ship could be floated and again in condition to re- 

 sume work. Notwithstanding these delays, the following lines have 

 been run thus far : — 



1. One line from Havana to Sand Key in depths of from 320 fathoms to 951 

 fathoms. 



2. A second line on the coast of Cuha from Havana to a short distance west 

 of Bahia Honda, from 292 fathoms to 850 fathoms. 



3. A short line of about 40 miles northerly from the Tortugas, from 1 1 1 

 fathoms to 37 fathoms, to examine the character of the Fauna of the Florida 

 Bank to the westward of the mainland as far as the 100-fathom curve. 



4. A line frum the lOO-fathoni ciu:ve on the west side of the Florida Bank 

 about 30 miles north of tlie Tortugas, across to the 100-fathom curve on the 

 northeastern side of the Yucatan Bank, from 110 fathoms to 1,920 fathoms to 

 95 fathoms. 



5. A line from 1,568 fathoms north of the Alacran Reef, from the deep 

 basin extending from the northern slope of the Yucatim Bank toward Vera Cruz 

 up to 84 fathoms on the northern edge of the Yucatan Bank. 



6. A line from the 100-futhom curve on the north side of the Yucatan Bank 

 to Alacran Reef, then in a soutlieast direction from there into 20 fathoms off 

 the Joblos Islands diagonally across the Yucatan Bank. 



7. A line in the trough of the Gulf Stream from north of Cape San Antonio 

 to Sand Key, Florida, from 1,323 fathoms to 339 fathoms. 



In all, about 1,100 miles of lines, taking the shortest distances from 

 point to point. 



The Fauna of the Yucatan Bank is identical with that of the Florida 

 Bank, being characterized by the same species of Echinodcrms, Mol- 

 liisks. Crustaceans, Corals, and Fishes, so well known already from 

 shallow water on the Florida side. While on the Yucatan Bank I had 

 the chance of examining the great Alacran Reef, an excellent plan of which 

 is given on one of the British Hydrographic maps of tlie Gulf of Mexico. 

 It is one of the circular reefs resembling atols, and I was the more desir- 



