No.4175.] MORTH-AMERICAN INVERTEBRATES. 733 
d2. Dorsal gap of the corona very wide ; tube opaque, regular, 
tapering slightly from top to bottom . . 30, O. intermedius 
Davis (Fig. 23) 
c3. Antenne long 
dr. Antenne very long and recurved, tube floccose ; very small 
1, O. longicornis Davis 
d2. Corona large, nearly circular, crossed with thick ribs, tube 
oose, very irregular, clay colored . 32, O. umbella Hudson 
42. Not attached ; inhabiting a tube ; individuals separate or one adult 
grouped with its youn 
ór. Corona horseshoe-shaped ; two antenne on the ventral surface 
of the body, united almost to their tips 33, Conochilus dossuarius 
udso 
43. In clusters of many individuals, forming usually a spherical colony, 
appearing to the naked eye as a small yellowish or grayish ball 
br. Clusters attached 
cI. Body (in known American species) with two or four opaque 
warts in a transverse row on the ventral side. No tube. Corona 
broad, kidney-shaped, with short axis dorso-ventral; antennz 
inconspicuons ig. vd sc s xd ie Megalotrocha 
dr. Opaque wartstwo. . . . . . . 34, M. semibullata 
Hudson (Fig. 24) 
da. Opaque warts four . . .... 2 oe 35, M. alboflavicans 
r. (Fig. 25) 
c2. Dwelling in transparent gelatinous tubes ; body without opaque 
warts or denticles ; corona heart-shaped with long axis dorso- 
ventral; antennz inconspicuous. 36, Lacinularia socialis Ehr. 
62. F ree-swimming colonies or clusters . . . . . . onochilus 
cI. Antenne two, separate except at the base, situated on the 
corona, between the mouth and the ventral gap ; colonies spheri- 
cal, of many individuals . . . . 37, C. volvox Ehr. (Fig. 26) 
£2. Antennz united, so as to appear single, large and conspicuous, 
and situated on the corona; clusters usually unsymmetrical and 
containing comparatively few individuals . . 38, C. unicornis 
Rousselet (Fig. 27) 
C. dossuarius — see No. 33) 
42. Not fixed when adult ; not forming colonies nor living in tubes (in 
a few rare cases the animal lives in a tube, but is never attached by its 
foot to the bottom of the tube, as in 47 
Br. Without lorica; i.e., the cuticle of the animal is flexible, not stiffened 
to form an unyielding armor or Zorica 
#1. Swimming with the corona and creeping like a leech ; body usually 
nearly cylindrical (dorsal and ventral surfaces not being conspicuously 
differentiated), and composed of rings which may be drawn one within 
the other in a telescopic fashion. Foot (reckoned from the cloaca to 
