NASSIDA. 157 
ster pots, etc., the Nassa itself is frequently caught, attracted 
thither by odors savory. 
Nassa reticulata is said to be very destructive in the oyster- 
pares of Arcachon (France). It is so numerous that a single 
tide has yielded 14,600 specimens within a space of 40 French 
hectares (= about 100 acres). The adult Nassa will bore through 
the shell of an oyster three years old within eight hours; but 
the young shells are far more destructive, because they select the 
tender shells of the very young oysters, sometimes piercing 
fifteen or twenty in succession before their hunger is satisfied. 
An oyster a month old is destroyed in a half-hour. 
According to M. Lespés, N. reticulata is preyed upon by a 
parasitic Trematode (Cercaria sagitata) which infests its liver. 
Its spawn-cases are deposited on the leaves of Zostera and on 
various other things which are left dry only at spring-tides ; the 
capsules are arranged in rows, and so closely that they overlie 
each other “like the brass scales of the cheek-band of a hussar” 
(Johnston). They are compressed pouches, each of the size of 
a large spangle, supported on a very short stalk, with a small 
opening at the top to allow the fry to escape. Mr. Peach has 
given us some amusing particulars of the fry. These behaved 
themselves like the fry of other gastropods, skipping about and 
whirling round by means of their ciliated lobes, apparently in 
a state of pleasurable excitement; but it seems that the exercise 
was compulsory or necessary to prevent the attacks of a swarm 
of infusoria, which made short work of any tired or feeble infant 
Nassa. 
The following “subgenera” may be retained as convenient 
group designations, although the species, varying much in their 
sculpture, cannot always be positively assigned : 
ARCULARIA, Link. (Eione, Risso.) Body-whorl gibbous on 
the back; spire produced; callus of inner lip greatly extended 
and covering the spire. N. Thersites, Brug. ‘lii, 82, 83). 
NAyTIA, H. and A. Adams, Shell smooth; aperture with a 
channel at the hind-part continued up the spire. N. glabrata, 
Sowb. (lii, 84). 
ALEcTRION, Montf. (Monoceros, Fleming.) Spire elevated, 
whorls glabrous, polished or papillary; inner lip spreading ; 
outer lip denticulate, not variced externally. N. glans, Linn. 
(lii, 85). 
zEUXIS, H. and A. Adams. (Telasco, H. and A. Adams. 
Nassodonta, H. Adams. Zaphon, H. and A. Adams.) Spire 
elevated, smooth, or longitudinally plicate, polished; inner lip 
with the callus defined, or somewhat spreading ; outer lip exter- 
nally variced, sometimes dentate anteriorly. N. canaliculata, 
Lam. (lii, 86, 87). 
AcicuLiIna, H.and A. Adams. Shell turreted, polished, smooth, 
