196 A. EF. Verrili— Results of Recent Dredging 
thick, specific gravity 1°66. The nucleus portion measured 
one way | 3 inches, the other way 12 inches; specific gravity 
1:71. While the three outer layers were yellowish-brown the 
nucleus portion was dark-brown, making a distinct contrast in 
color. 'The following are the analyses of the different layers ; 
Ist layer. 2d layer. 3d layer. Nucleus portion. 
PO, 28°10 28°14 28°34 28°14 
MgO 16°84 16°87 16°88 16°58 
(NH,)OH 12°57 12°59 12°61 12°61 
H,O 72 41°80 41°66 41°96 
Residue insol. in HNO, *74 .58 58 "60 
99°97 99°98 100°07 99°89 
On igniting the substance at a red heat all the water and am- 
monia was driven off, thus giving the amount of these two 
substances. Then determining the ammonia directly by means 
of magnesia and deducting from the total volatile matter the 
amount of water was thus indirectly obtained. 
These analyses show that this calculus is. composed princi- 
pally of ammonio-magnesian phosphate, and that the different 
ayers are essentially the same. By making thin and polished 
sections of the different layers and examining them under the 
microscope with a half inch objective, they were found to be 
amorphous, but divided into layers by what seemed to be fine 
black lines, and on examination with a fifth of an inch objective 
these lines were resolved into fine black specks which may be 
looked upon as impurities in the phosphate, with regular 
arrangement, and which are insoluble in nitric acid. With 
Sima light a fine arrangement and display of colors was 
obtained. 
The other two caleuli were not at my disposal for analysis, 
but from their exact resemblance to this in external and in- 
ternal structure and color, there is no doubt but that their 
*)e . 
composition is the same. 
Art. XX VIIL.—Brief Contributions to Zoology jrom the Museum 
of Yale College. No. XXXIV.—Results of Dredging Expedt- 
tions off the New England Coast in 1874; by A. HK. VERRILL. 
[Continued from p. 43.] 
OuR investigations show conclusively that there is a very 
decided flow of cold currents through Fisher’s Island Sound 
ike pri Island pad into Long Salned Sound, and er 
the deeper parts of the latter for a great distance, especially 
toward the southern and deeper side. The influence of this 
