ERYCINIDA. 219 
sitic. In one sense only can it be said to live on echinoderms. 
The food of Spatangus purpureus, on which it is usually found, 
appears to consist of animalcule; and for that purpose it 
swallows large quantities of shell-sand, causing thereby a strong 
and frequent current in the neighborhood of its mouth. The 
Montacuta probably avails itself of this in-draught, and partakes 
of the sustenance intended for the Spatangus, placing itself in 
the way, with its alimentary tube or opening turned in the right 
direction. No exudation of the Spatangus has been noticed ; 
and its excretions would scarcely be produced in sufficient 
quantity for the support of the Montacuta, or perhaps be suitable 
to it. The latter has no suctorial organ,such as is possessed by 
all animal parasites ; it never attaches itself to the pedicellarize 
or any other soft part of the echinoderm; nor has it once been 
detected on the back or sides, or elsewhere than in the ventral 
region of its associate. It is only found on the spines close to 
their points.” —J EFFREYS. 
TELLIMYA, Brown, 1827. Shell transversely oval, surface a little 
rugose; beaks prominent, acute; hinge with a pit for the liga- 
ment, which contains a small ossicle, and a triangular cardinal 
tooth on each side of it in the right valve, and two distant rudi- 
mentary lateral teeth in the left valve. TZ. bidentata, Mont. (cxx, 
86). Europe. 6sp. Eur., Cal., Japan. 
KELLIELLA, M. Sars. 
Distr.—K. miliaris, Phil. (exx, 87-89). Europe. 
Shell minute, orbicular, tumid ; umbones slightly prominent, 
incurved ; lunule cordate, distinct; ligament minute; surface 
white, without epidermis, concentrically striate; cardinal teeth 
two, laterals none. 
Lasza, Brown, 1827. 
Syn.—Poronia, Recluz, 1843. Cycladina, Cantr.(pars). Kellia 
(pars). Bornia (pars). 
Distr.—9 sp. Universal. Fossil; Tertiary. LZ. rubra, Mont. 
(exx, 90). 
Animal with the mantle folded on the anterior side so as to 
form a wide but incomplete incurrent tube; the excurrent tube 
is inconspicuous, placed on the opposite side; foot long. 
Shell minute and roundish oval; beaks straight ; cartilage long, 
placed at the shorter end of the shell, contrary to that in Kellia ; 
left valve with a minute thorn-like cardinal tooth; and in each 
valve two remarkably strong lateral teeth. 
The genus is intermediate between Montacuta and Kellia. 
“The Lasse usually inhabit the littoral zone, where they con- 
gregate in vast numbers at the roots of small sea-weeds, in the 
crevices of rocks, and in empty shells. LZ. rubra, a British spe- 
