406 ZOOLOGY. 
Cxass II. Leprocarpi1 (Lancelet). 
The lancelet is the only type of this class. From ite 
worm-like form it was regarded as a worm by'some authors, 
merit careful study. 
The mouth is oval, surrounded 
with a circle of ciliated tentacles 
supported by semi-cartilaginous pro- 
cesses arising from a circumoral ring. 
The mouth leads directly into a large 
broad pharynx or ‘branchial sac” 
(Fig. 387, d), protected at the en- 
t ys 
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yRPe and as a mollusk (‘‘Limax”) by 
2 g8e Pallas. The body is four or five cen- 
gea° 8 timetres in length, slender, com- 
Teel pressed, pointed at each end, hence 
Be £EE the generic name (Amphiozus, auqi, 
pe 28 both, o&vs, sharp), the head-end be- 
Oso . . 
e323 on. ing thin, compressed. The muscu- 
EESas ? P A 
Seas Li -lar segments are distinct to the 
£3" QR. & 
$ Bee y.. naked eye. From the mouth to the 
oe Bee vent is a deep ventral furrow, and 
BU oEe a slight fin extends along the back 
QEMr8 & 8 
REesS and ventrally as far front as the vent. 
oQ Bes re 
Bg ou L. The lancelet, A. lanceolatus (Pal- 
2 wD fiw . . . 
E Lee las), lives in sand just below low- 
Deen . 
abEe y water mark, ranging on our coast from 
oO 
Page 7 4 the mouth of Chesapeake Bay to 
g = ae Florida; it also occurs on the South 
see American coast, and in the European 
Saas = . . 
2255 seas and the East Indies, the species 
S . . 
oa, being nearly cosmopolitan. 
Be Be As this is the lowest Vertebrate, its 
Uese structure and mode of development 
eee P 
B° 
es 
B 
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2g 
~Eo. trance by a number of minute cili- 
Siang 2 ated lobes. 
Sele The walls of this sac are perforated 
by long ciliated slits, comparable with those of the bran- 
