1874.] Anatomy and Habits of the Genus Phronima. 155 



the narrow area of the tallow-arming of the deep-sea lead to include for- 

 tuitously, and carry down Phronima or any other little crustacean natu- 

 rally living near the surface ; and contact with the bottom would finally 

 press it into the tallow, so as to mislead the observer as to its true 

 habitat. Conversely, in bringing up the dredge from a given depth, it 

 may finally carry with it any more superficial objects casually lying in 

 the track which it takes. 



Fig. 1 of the accompanying drawings from nature represents a species 

 of Phronima captured in lat. 30 16' S., long. 176 27' "W., of which I 

 find the following description in my notes taken at the time : 



Head exceedingly elongated from above downwards, with considerable 

 enlargement of the back part, which contains two masses of transparent, 

 rounded ?, and tapering columns, whose bases occupy the fulness of the 

 poll, exhibiting a regularly facetted appearance externally on two rounded 

 protuberances. The apices of these organs, on the other hand, con- 

 verge and blend with the rays of the compound eye, of which, indeed, they 

 may be said to form part, probably assisting nocturnal vision by the pro- 

 duction of luminosity. The long axis of the head is therefore at right 

 angles with that of the body, its form being full above and gradually 

 tapering downwards. The aperture of the mouth is situated at the 

 smaller extremity, inferiorly guarded by its mandibulse, maxillae, and one 

 pair of foot-jaws, appertaining to the cephalic segments. The latter 

 organs are more distinctly recognizable than the others, on account of 

 their more superficial position. They are short, apparently united at the 

 base, and curved forwards, terminating in two ovate and acute appen- 

 dages lying side by side, serrated on the borders and beset with short hairs. 



The eyes are small where the facets are lateral, and the apices are 

 invested with black pigment, but large where they swell out the back of 

 the head, the points of the same cones meeting in a red spot, quite distinct 

 from, and internal to the black one. This condition is also observable in 

 the Hyperians, and is worthy of further study in a physiological point of 

 view. 



Two minute two-jointed antennae arise from the head, just above and in 

 front of the eyes. The posterior or upper surface of the second joint of 

 these antennae is clothed with short stiff hairs. 



There are seven pairs of thoracic limbs ; but the first two are separated 

 from the others, to some little extent, by arising on a plane anterior and 

 inferior to them, the first two tergal pieces being somewhat wider than 

 those of the succeeding segments. They are, moreover, distinguished 

 from the other limbs by possessing a minute spine-like movable claw, 

 bounded, on either side, by a short styliform process. There is also a 

 rudimentary manus developed upon the posterior part of the second seg- 

 ment above this claw, that of the first pair being the stoutest, although 

 the limbs themselves are the smaller of the two. Both pairs of members 

 now described, while they very distinctly belong to the thorax, act the 



N2 



