174 REPORT—1843. 
may have a double or treble series of representations, in which case they are 
very generally parallel. The following examples from the A®gean fauna 
will serve to illustrate the representation in depth. 
Laake ss: ‘ee boysii. Min. IT. Max. III. Min. V. 
Ligula profundissima. Min. VI. Max. VIII. 
(cee margaritacea. Min. II. Max. IV. Min. VI. 
Ribena Nucula polii. Min. V. Max. VIII. 
tne emarginata. Min. II. Max. IV. Min. V. 
Nucula striata. Min. IV. Max. VI. Min. VIII. 
Cardium papillosum. Min. IJ. Max. IV. Min. VI. 
Carprum. earitan minimum. Min. VI. Max. VIII. 
Cardita calyculata. Max. I. 
CarDITA,. | Cardita trapezia. Min. I. Max. IV. Min. VI. 
Cardita squamosa. Min. IV. Max. VI. Min. VIII. 
barbata. Max. I. 
Asse {ee Min. I. Max. IV. Min. VIII. 
scabra. Min. IV.? Max. VII. Min. VIII. 
imbricata. Min. V. Max. VIII. 
(ere: Max. II. Min. III. 
exiguus. Min. II. Max. V. Min. VII. 
Toons | ziziphinus. Min. III. Max. IV. Min. V. 
millegranus. Min. V. Max. VII. Min. VIII. 
variabilis. Min. I.? Max, II. Min. IV. 
NASssA... | satin Max. IV.? Min. V. 
intermedia. Min. V. Max. VII. Min. VIII. 
In cases equally evident, but where the maxima and minima are not so 
definite, the succession of representations may be exemplified thus : 
feameta. Ill. IV. V. 
cuneata. 
Lima .. V. 
elongata. VI. VII. VIII. 
granulata. I. II. 
Rissoa . cimicoides. II. III, IV, V. VI. 
reticulata. V. VI. VII. VIII. 
Genera like species have a fixed maximum of development in depth, not 
being irregularly distributed in the several zones, but presenting their greatest 
assemblage of species in some one, whilst the numbers fall away more or less 
gradually in the preceding and following zones. In making calculations of 
the maxima of genera in depth, we must be careful to exclude all stragglers 
from the zones in which they may occur, otherwise our figures will be un- 
true. In the following table I have exhibited the specific distribution in 
depth of such of the AZgean genera as present the greatest number of species. 





Aegean! y. | 1. | IU. | IV. | V. | VL. | VIL | VII. 
| Cardium)!5.0: } 9 2 3 3 6 3 KE] 1 af 
Péuten! tis 2.2% 14 0 4, 6 8 9; 11 4, 5 
LUTE ao en mmeoe eee tte [i 5 6 8 8 6 g 1 2 | 
Rissoa it s.2 Q1 | 14] 10 7 7 3 3} 3 2 
Trochus...... 98 - LOs LOnels Lo 9 if 5 1. | 
Pleurotoma....| 24} 3] 5] 7410) 11 9.4. 8 Poa 
INGSSH) Fes. rele 14 3 6 4: 4 ] 4 1] 1 
| 

