v1 PAGURIDEA—L/THODES MAIA 177 
reduced and carried tightly flexed on to the ventral surface of 
the thorax. They live a free, unprotected existence, and are 
highly calcified. They are, however, certainly Pagurids, as is 
evidenced by a number of anatomical characters, but most 
clearly by the asymmetry of the abdomen, especially in the 
female, which is not only markedly asymmetrical in the arrange- 
ment of its dorsal plates (Fig. 121), but also in the presence of 
Fig. 121.—Zithodes maia, @, in ventral view, x }. The abdomen is flexed on the 
thorax, so that its dorsal surface is seen. 0.5, Lateral plates of third abdominal 
segment ; 1.5, left lateral plate of fifth abdominal segment ; m, marginal plate ; 7, 
brush-like last pereiopod ; Ze.6, telson and sixth abdominal segment. 
three pleopods upon the left side only, as in Birgus. The male 
is without these appendages, and the sixth pair of pleopods is 
absent in both sexes. The remarkable calcified plates upon the 
abdomen bear a superficial resemblance to those in Airgus, but 
their evolution is traced, not from a Cenobite, but from an 
Eupagurine stock.’ 
In some of the Eupagurinae, e.g. Pylopagurus, feebly calcified 
plates are present upon the segments of the abdomen 
(Fig. 122, A). . 
In the most primitive of the Lithodidae we witness the 
1 Brandt, Bull. Phys. Math. Acad. St. Pétersbourg, i. p. 171, and viii. p. 54 ; 
Boas, K. Dansk. Vidensk. Selskab. Skrift. Naturvid. og Math. Afd. 6, Bd. 2, 1880; 
Bouvier, Ann. Seti. Nat. (Zool.) (7) xviii. p. 157. 
VOL. IV N 
