1881.] The Fauna of the Nickajack Cave. 881 
fish (Orconectes hamulatus Cope’). It is quite different from O. 
pellucidus of Mammoth and Wyandotte caves, in the rostrum, the 
slender hands, the much broader antennal scale, and in the form 
of the gonopods, while the whole creature is slightly slenderer 
than O. pellucidus, though the rudimentary eyes are of the same 
proportion to the neighboring parts as in the other species. 
It is obvious that the form from which O. hamulatus has been 
derived, is quite different from that which has given origin to the 
blind crawfish of the Kentucky and Indiana caves. The most 
common species in Northern Georgia is Cambarus latimanus, it 
having been found at Athens and Milledgeville, Georgia, and 
probably being abundant in the northern’ limestone region of 
Alabama. At any rate it is perhaps to Cambarus latimanus that 
'1In this species the teeth of the mandibles are usually much sharper than in the 
other blind species, there being three well marked sharp posterior teeth in O. hamu- 
Zatus, which in O. pellucidus are represeited by low, obtuse, nearly obsolete teeth ; 
though in different specimens the obtuseness of the teeth vary. The epistoma is 
much as that of C. dartonii, but shorter and broader; while the median terminal 
tooth is less marked than in C. /a¢imanus, and the sides fall away rapidly from the 
front margin. It is entirely different in shape from that of O. pellucidus. The an- 
tennal lamina is shorter, broader and much more rounded on the inner edge than in 
O. pellucidus, and in this respect differs from C. Jatimanus. The rostrum is nar- 
rower than in O. pellucidus, while the first pair of (large) claws are much slenderer, 
and the telson narrower than in O. pellucidus. The most obvious difference is 
seen in the modified first and second pairs of abdominal feet of the male, to which 
we may apply the term gonofod, for it is not properly an intromittent organ. The 
first and second pair of gonopods differ decidedly from those of O. pelluctdus, and 
closely resemble those of Form 11 of Cambarus latimanus (from Athens, Georgia, 
figured by Hagen), those of the first pair being shorter, thicker and the last joint 
being much bent, hock or sickle-shaped, whence the specific name Aamulatus. The 
first gonopods differ in the proportion of parts from those of C. /atimanus, but the 
joint is much more acute than in C, Zadimanus. 
The first pair of gonopods, compared with the /atimanus form of odesus from 
Maryland, given me by Mr. Uhler, are much like it in general form, but the sinuous 
branch is longer and straighter, while the hook is much slenderer. In the second 
pair of accessory gonopods the knob is proportionately smaller. In other more 
important characters O. hamulatus is quite unlike the /atimanus form of C. obesus, 
the scale of the second antennz being very different and the chelz one-half as wide, 
and the antennz much longer, while the rostrum is much longer and more pointed. 
Length of the largest male, 5 centimeters. 
Note on the function of the Gonopods.— As stated by Milne Edwards and others, 
the gonopods of the crawfish are not intromiitent, but simply rude gutters for the 
passage of the fertilizing fluid to the eggs. It is obvious that in the lobster the gon- 
opods form simply a rude tube or gutter to conduct the seminal fluid to the eggs as 
they pass backward from the oviducts to the swimming feet of the female. During 
the process of fertilization of the eggs, the male, without doubt, as in the crawfish, 
holds the female by the claws, she resting on her back. The term gonofod is ap- 
lied for convenience in descriptive carcinology to the external reproductive organs 
of the crustacea, since they are only modified limbs.—(A. S. PacKarD, JR.) 
VOL, XV.—-NO. XI, 6x 
