18 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
The eye-stalks in Calliaxis are slightly flattened and are pro¬ 
portionally longer than in Naushonia. 1 he anterior peieiopods 
(clielicipeds) are very large with a long, slender dactylus and are 
perfectly chelate. The shape and proportions of the posterior 
pereiopods are more as in Naushonia. According to ITeller s 
descriptions, the second and fifth pairs are slightly subchelate, but 
Cano describes them as simple. 
The form of the mandibles cannot be definitely deduced from 
descriptions or figures (pi. 3, figs. 43, 45). If the blade is not exca¬ 
vate, which is a possible interpretation, we have here an important 
difference from Naushonia. Its border is without teeth. The man¬ 
dibular palp is proportionally rather long, three-jointed, and the 
apical joint is densely hairy. 
From the foregoing comparison of the adults, we can scarcely 
doubt that Naushonia and Calliaxis are allied genera, although 
occurring in widely separated localities. They must then be con¬ 
sidered together in any systematic arrangement of the Thalassinoid 
Crustacea, and data derived from knowledge of one will be valuable 
in indicating the affinities of the other. Unfortunately the same 
uncertainty that has already been noted with respect to Naushonia 
holds good for Calliaxis also. Its position has always offered diffi¬ 
culties to systematists, and with the exception of Heller, in 1862, 
and Bate (’ 88 ) and Ortmann (’ 98 ) in more recent years, carcinolo- 
gists have avoided a definite expression of opinion. These authors 
also place the genus more or less tentatively, and their assignments 
are diverse. Heller makes it part of his “family” Thalassinidae , 
a group with the rank and almost the same scope as the modern 
“division ” Thalassinidea, and suggests that it comes near de Haan’s 
genus Laomedia. This latter genus, however, is only imperfectly 
known, so that the correctness of this conclusion cannot be properly 
tested, and even if confirmed, would be of little assistance. Bate 
(’88) groups Calliaxis, Calocaris, and Thaumastocheles in one family, 
Thaumastochelidae , which he places in his Macrura aberrantia, i. <5., 
nearer to the Thalassinids than to the Nephropsidea, which form 
part of his Macrura normalia. He does not mention the genus 
Laomedia. The reasons for this union of Calocaris with Thauma¬ 
stocheles, however, are not at all apparent, and although Calliaxis 
resembles the latter genus in the structure of its antennae, maxillae, 
and second maxillipeds, it does not seem to lie very close to it. 
