136 MOLLUSCA. 



behind, connecting it with the sac, and with two other 

 frena, connecting it with the sac before. 



"Sp. 1. Cranchia scabra. Sac rough, with hard, rough 

 tubercles. 



" Sp. 2. Cranchia maculata. Sac smooth, beautifully 

 mottled with distant ovate spots." (Narrative of an Ex- 

 pedition to explore the river Zaire, usually called the 

 Congo in South Africa, in 1816, under the direction of 

 Captain J. K. Tuckey, R. N. London, 1818, p. 410.) 



Head surrounded with Eight Arms without Feet. 



The suckers have soft margins. The sac is destitute of 

 fin-like expansions, and is either simple or strengthened in 

 the interior by two short corneous processes. The head is 

 united with the sac behind, without the intervention of n 

 neck. 



a. Arms all equal in Size. 



GENUS OCTOPUS. Suckers arranged in a double row. 



The suckers are sessile. The oviduct is double. The 

 margin of the anus is simple. The Sepia octopodia of Lin. 

 is the type of the genus. 



GENUS ELEDONA. Suckers on the arms disposed in a 

 single row. 



M. Lamark has figured and described two species of this 

 genus, in the Mem. de la Soc. (THist. Nat. One of these is 

 a native of the Mediterranean, and is remarkable for giving 

 out an odour like musk. 



b. Arms unequal. 



GENUS OCYTHOE. Two of the arms at their inner ex- 

 tremities furnished with membranaceous expansions. 



In this genus, which was instituted by M. Rafinesque, 

 the suckers are in a double row, and supported on foot- 



