IV ACROTHORACICA—ASCOTHORACICA 93 
distinguished from all the foregoing Cirripedes by the presence 
of a well-developed abdomen. Since the discovery of other 
allied genera, 1t has been decided that the abdomen is equally 
reduced in these forms, and that the terminal appendages do not 
belong to this region, but to the thorax. 
The sexes are separate. The body of the female (Fig. 64, A) 
is enclosed in a chitinous mantle, armed with teeth by which 
the excavation is effected,and is attached to the cavity in the 
host by means of a horny disc. Upon this disc the dwarf 
males (B) are found. 
Alvippe lampas inhabits holes on the inner surface of dead 
Fusus and Buccinum shells; Cryptophialus minutus the shells 
of Concholepas peruviana; C. striatus’ the plates of Chiton; 
Kochlorine hamata the shells of Haliotis; and Lithoglyptes 
varians Shells and corals from the Indian Ocean. 
Sub-Order 4. Ascothoracica. 
These are small hermaphrodite animals completely enveloped 
in a soft mantle, which live attached to and partly buried in 
various organisms, such as the branching Black Corals (Gerardia). 
They retain the thoracic appendages in a modified state, and the 
body is segmented into a number of somites, the last of which 
probably represents an abdomen. 
Laura gerardiae, described by Lacaze Duthiers,” is parasitic 
on the stem of the “ Black Coral,” Gerardia (vol. i. p. 406); it 
has the shape of a broad bean, the body being entirely enclosed in 
a soft mantle, with the orifice in the position corresponding to 
the hilum of a bean. The body lying in the mantle is composed 
of eleven segments, and is curved into an S-shape. Its internal 
anatomy is entirely on the plan of an ordinary Cirripede. 
Petrarca bathyactidis, G. H. Fowler,> was found in the 
mesenteric chambers of the coral Bathyactis, dredged by the 
Challenger from 4000 metres. The body is nearly spherical, 
and the mantle-opening forms a long slit on the ventral surface. 
The mantle is soft, but is furnished on the ventral surface with 
short spines. 
_The antennae, which form the organs of fixation, remain 
1 Berndt, Sitzb. Ges. Naturfr. Berlin, 1903, p. 436. 
2 Arch. Zool. Exp. viii., 1880, p. 537. 
OUONE. i. Micr, Sct. Xxx.,, 1890, p: 107. 
