Dr. J. Young on the Malacostraca of Aristotle. 251 



Organs of Sense. — Sensation (or, more correctly, sensibility) 

 Aristotle held to be essential to all animals. This logical infer- 

 ence rendered necessary the logical heart just mentioned, which 

 is thus assumed to exist on grounds very far from practical*. 

 The special senses possessed by the Malacostraca are those of 

 taste and vision, smell and hearing. The first resides in the 

 tongue, sight in the mobile eyes. The place of eyelids is sup- 

 plied by the hardness of the eye. To counterbalance the dim- 

 ness of vision supposed to result from thus, so to speak, looking 

 through the hard eyelid, motion is given to the organ, so that 

 it may turn towards the light (De Part. ii. 13). Smell and 

 hearing are referred to no special organ ; the former is held to 

 exist because baits are used with success in the capture of these 

 animals. The olfactory sacs of Rosenthal (auditory of Farre) 

 were necessarily unknown, as was also the capsule at the base of 

 the outer antennas, to which the function of hearing is ascribed. 

 Both organs are as yet known in only a small number of the 

 class ; while the phenomena ascribed to these two senses are 

 experimentally demonstrable as at least in part due to the 

 operation of the other senses. 



Generative System. — The existence of penetrating organs is 

 expressly denied in the case of Carcinus; and their absence in 

 the group generally is the basis of remarks on impregnation, to 

 which we shall again recur. The genital apertures beneath the 

 last pair of feet in Caris are mentioned, but, as will appear, with 

 no reference to their true function. The ova are alongside of 

 the gut — a general remark applicable to all the group (H. An. 

 iv. 2. 11). In Carabus a duct is described as passing from 

 thorax to vent, on the lower surface of the fleshy mass. It 

 is present and identical in both sexes, being devoted to the 

 proper secretion of each. The successive branching of these 

 ducts is not mentioned here, but occurs in the 'De Genera- 

 tione 5 (i. 17). Not only are they similar in aspect; their con- 

 tents, a pale fluid, are similar also. This could only have been 

 a note descriptive of their appearances in specimens examined 

 after reproduction ; for in a subsequent chapter the ovary of 

 Carabus is said to be contracted at intervals (e%et ivTOfMis), its 

 appearance during the earlier period of gestation ; and the red 

 colour of the eggs, which he knew of, could not have escaped 

 notice, had they been seen previous to extrusion. 



Another teleological enigma is presented by the male genital 

 organs. Testes are intended as regulators of, or rather checks 

 upon, the procreative instincts (De Gen. i. 4) ; in animals of 

 cold habit they are therefore unnecessary. But the passages 



* Compare De Anima, i. 5 et seq., ii. 2. 11 ; De Part. ii. 8. 10, iv. 5. 



