134 Memoirs of the Indian Museum. [Vor. IV, 
spinules), one or two intermediate denticles and one lateral. Ventral process of 
uropods terminating in two sharp spines, inner usually shorter than outer. 
There are no well-marked secondary sexual distinctions. 
Ten species of this genus are known; nine have been found in Indo-pacific 
waters and one, O. havanensts, in the Atlantic. No species is known to inhabit both 
areas. 
Specimens of Odontodactylus are, unfortunately, not numerous in collections 
and consequently little is known of the variation that occurs within the limits of 
the species and of the alteration in form due to growth. In taxonomic work the 
precise number and disposition of the carinae on the telson is of great importance, 
but this is a character that may perhaps be modified in the course of growth from the 
post-larval form to the adult. Another feature which appears to have considerable 
systematic value is the size of the eye. In Squilla the breadth of the cornea is 
known to decrease proportionately during growth and this, if true in Odontodactylus, 
must have much influence on our views of the limits of the various species. Exami- 
nation of seven specimens of O. sowthwelli, varying from 21 to 37 mm. in length, 
seems, however, to indicate that this proportional difference, due to growth, is not 
one of any considerable magnitude, at any rate in that form. 
The species appear to live on rough ground, but of their habits nothing precise 
is known. The greatest depth from which any member of the genus has been 
obtained is 163 fathoms (O. havanensis, Bigelow). 
For explanation of the terminology used below in designating the carinae of the 
telson, see text-fig. 4, p. 12. 
Key to the species of Odontodactylus. 
I. Dactylus of raptorial claw with only two or three teeth on its inner margin. 
A, Several carinae on sixth abdominal somite, six of them terminating pos- 
teriorly in spines ; several carinae in anterior half of telson on either side 
of median crest. 
I. Raptorial dactylus with two teeth; second lateral carinae of telson 
present. 
A. Breadth of cornea about one-fifth median length of carapace ; raptorial 
dactylus very strongly dilated at base ; median crest of telson not 
remarkably high, with two pairs of submedian carinae .. .. scyllarus, p. 135. 
B. Breadth of cornea about one-third median length of carapace ; rapto- 
rial dactylus not very strongly dilated at base ; median crest of telson 
remarkably high with a single pair of submedian carinae 
.. cultrifer, p. 137. 
II. Raptorial dactylus with three teeth ; second lateral carinae of telson ab- 
sent (breadth of cornea about one half median length of carapace) .. carinifer, p. 138. 
B. Sixth abdominal somite without carinae, with only four posterior spines, 
submedians and postero-laterals ; telson with median carina only .. elegans, p. 13g. 
I, Dactylus of raptorial claw with at least six teeth on its inner margin. 
A. Second \ateral carina of telson present. 
1. ‘Telson with two pairs of submedian carinae ; second lateral carina run- 
ning to apex of lateral marginal tooth (text-fig. 4, p. 12) .. japonicus, p. 139. 
II, ‘Telson with a single pair of submedian carinae; second lateral carina 
