314 Geographical Distribution of Crustacea. 
September to February inclusive. The subject is one in which 
it is difficult to come to numerical results, because the variations 
effect, and distant action sometimes causes local effects. The 
whole rise and fall is nearly three-quarters of a foot. 
he mean level of the water deduced from the mean of high 
and low water in each month is shown in the annexed table. 



TABLE No. 9. 
| Mouth. Height in feet. Month. Height in feet. 
June, Seah a 5°60 December, - 5°31 
July, = SUM, Sas 78 January, - - - Z 
August, - - - 63 February, - * - 15 
September, - - 93 March, i - < 26 
October, - - - ‘90 Apr rs = 2 3 96 
November, me tee 713 Mie os) Stew ide. 32 
5°76 5:24 






Art. XXXIV.—On the Geographical Distribution of Crustacea; 
by James D. Dana.* . 
In volume xvi, of this Journal, the author presented a chart 
of oceanic isothermal (or rather isocrymal) lines, for the illustra- 
tion of marine zoological geography, prepared more especially 
with reference to the geographical distribution of Crustacea, and 
taken from his Report on the Crustacea of the Exploring Expe- 
dition around the world under Capt. Wilkes. . The following }S 
a brief abstract of the remainder of the Chapter on the Distribu- 
tion of Crustacea; the Tables which occupy near 30 pages are 
omitted besides other details. 
he lines on the chart, it may be here repeated, are lines of 
equal winter (or coldest month) temperature for the water, the 
perature of coral reefs), 62°, 56°, 50°, 44°, 35° F. 
the lines of 68° F’. north and south of the equator lies the Tor- 
J one of oceanic water temperature; from the line of 68 
to that of 35°, the Temperate Zone; beyond the line of 35°, the 
Frigid Zone. These Zones are divided by the lines into Re- 
I TORRID ZONE. 1. Torrty Region on Sus-zonz, 74° and A 
2. Susrorrip # 68° to 74° 
IL TEMPERATE ZONE, 1. Warm Temperate - 62° to 69. 
2, TEMPERATE B 56° to 62, 
3. SuBTEMPERATE * 50° to 56 
4. Corp TEMPERATE * 44° to 50, 
5. § G. f 35° to 44 

_ IIL FRIGID ZONE. 
* From the Author's Report on Crustacea, (2 vols. 4to, 680 and 1620 pages) 
