360 Rev. A. E. Eaton on Rhacodes inscriptus, Koch, and 
tionship cannot be defined by means of the valves alone with- 
out the organs; still less can casts satisfy us in this matter. 
With regard to Mr. J. HE. Lee’s rare little specimens from 
Devon, in the absence of their valves we can do no more than 
refer them to the genus Primitia, defined in the Ann. & Mag. 
Nat. Hist. ser. 3, vol. xvi. p. 415, and point out that apparently 
their closest ally is the Lower-Silurian P. Barrandiana. It 
is, however, just possible that, had the casts not been modified 
by lateral pressure, fig. 1 a might have been much more 
Leperditioidal and like P. Tatec, whilst the posterior convexity 
in fig. 1 6 may have been increased, if not brought about, by 
the same cause. Under these circumstances it is not advisable 
to venture on a specific determination. 
XXXVII.—WNote on Rhacodes inscriptus, Koch, and Arma- 
dillo officinalis, Duméril, terrestrial Isopoda. By the Rev. 
A. E.-Haton, M.A. 
Dr. A. GERSTACKER, in a recently published part of Bronn’s 
‘Klassen und Ordnungen des Thier-Reichs,’ Bd. v. Abth. i1. 
p: 209, brackets Rhacodes, Koch, as a synonym of the genus 
Tylos, Latreille. As this combination, if unobjected to, is 
liable to cause trouble, it may be well to notify that the 
characters attributed by him to the genus apply in essential 
particulars to Tylos exclusively. 
Rhacodes inscriptus, Koch, described in Rosenhauer’s ‘ Die 
Thiere Andalusiens,’ p. 422 (1856), is a woodlouse very 
nearly akin to Armadillidium, Brandt and Ratzeburg (1833), 
judging from the make of its head and antenne, its tail-seg- 
ments, their modified legs, and their breathing-organs ; and 
in these distinctive structures it exhibits no affinity with Tylos. 
Koch’s description is sufficient for the recognition of the 
animal. ‘The most obvious difference between it and Arma- 
dillidium is in the eyes : those of this latter genus are multiple, 
whilst Rhacodes has only a single unfaceted eye on each side 
of its head. The species was found by Rosenhauer near 
Malaga at the end of April, not uncommonly. I have met 
with it in Portugal, near Porto, and at Ponte de Morcellos, in 
Beira Baixa, at altitudes of from 30 to 600 feet above the sea ; 
also in Madeira, where it is common at altitudes of 2500- 
5450 feet. In the Hope Museum at Oxford are four exam- 
ples, collected in the same island by the late Mr. Wollaston, 
without indications of altitude. 
