4,24. A HISTORY OF RECENT CRUSTACEA 
genus by Latreille, and points out that the figures of the 
type-species, T'ylos Latreillii, Audouin, in Savigny’s Plate, 
show the generic characters. Latreille in his ‘ Familles 
naturelles du Régne Animal,’ p. 567, 1825, merely says, 
‘Ajoutez immédiatement aprés le genre lygie, 'TYLOS 
(nouveau genre composé d’espéces marines), so that the 
information he offers is incorrect. Thus Savigny gave no 
name; Latreille gave a name, but did not effectively 
publish it; Audouin published the name, with a descrip- 
tion; the genus must therefore belong to him. But there 
is still a difficulty. In 1826 the name J'ylos was given 
by Van Heyden to a genus of Arachnida, and Budde-Lund 
assigns Audouin’s ‘Explication’ to 1827. M. Eugéne 
Simon. however, has explained that Van Heyden’s pro- 
dromus on the classification of the Acari merely named 
without defining the genus, and therefore did not effectively 
pre-occupy the name Tiylos. But Audouin’s preface is dated 
1825, and it seems possible, therefore, that the Crustacean 
genus was really published in advance of the Arachnid. 
M. Simon, on the contrary, says that the name T'ylos 
armadillo, Latreille, 1829, was published before the T'ylos 
Latreillit of Audouin’s ‘ Explication,’ which can scarcely 
be correct. Budde-Lund describes, besides the typical 
Mediterranean species, six others, including two made 
known by Krauss from South Africa. T'ylos spinulosus, 
Dana, is mentioned, and Tylos granulatus, Miers, from 
Japan, is distinguished from Krauss’s African species of 
the same name, as T'ylos granuliferus. 
Family 3.—Hellerude. 
The perzeon is as in the preceding family. The pleon 
has the first five segments fused, with two pairs of short 
lateral sutures marking off the third from the fourth, and 
the fourth from the fifth segment. The terminal segment 
is short, subquadrate. The first antenne are wanting. 
The spine-row of the mandibles has but two components 
on the left mandible, and is reduced to one on the right. 
The two pairs of maxille and the maxillipeds have the 
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