Worms, mollusc a. 39. Pterotrachea. 107 
59. I^TEROTIIACHExV. Body detached, 
gelatinous, with a moveable fin at the 
abdomen or tail : ^yes 2, placed within 
the head. 
Abdomen and tail furnifhed with finsj head wivh a round 
perpendicular probofeis, and a co/onet of lo fpincs on 
the front.. 
Nat, Mi/cell, tdh. 328. Ferjk. Arab, pt 117. 
Inhibits (he Met/itcrraneati and ^cb;pilago, _ 
Bciiy fubcylindrictl* about a fpan loivg and an inch in diameter; 
bead rounded on the fore-part and furniihed in front with a 
cornet of 10 conic fpines; beneath the coronet is the pro- 
bofcle, nearly z inches long, with a whitilh middle nerve, and 
thick hyaline tip and terminal mouth : feated on each 
■ fide the back of the neck internally, and remote : tmni near 
the fin beneath fptced with white; aidomen rough beneath, 
with an ovate pendnloua pouch before the fin : vettt acir the 
ligament of the tail: r «)7 vertical, an inch long, triangular, 
with 4.prickly lines each fide, and terminated each fide by a 
Jemicovdate horizontal pinnule: //j fituated beyond the middle 
of the body, orbicular, comprefled. and fixed to the white 
‘ lamintE of the trunk which arc crenate each fide ; beneath in 
the margin is another pinnule which i* bell-lfiaped, hyaline, 
and affixed by a middle point. 
Head elongated, projeiRiBg fanooth t fin central. 
Inhabits Forji. fn, Arab. p. 1 18. n, 4Z. 
Body hardly an inch long and very quick in motion ; eyes brown, 
at the bafe of the head ; bead not crowned by fpines ; fm 
roundifli. 
p 
Head obtufe hyaline * inteftine refpiratory and ciliate with 
plumes 
Inhabits — w-Forsk.yii, Arab, j^gipt. p, itS. ». 43. 
Body fubcylindtical> reddilh -hyaline : bead not diftinfl from. the 
trunk ; rj'w pellucid tranfverfe oval black : rra«i with a few 
whitilh dots beneath; fm roundilh longitudinal: intejiine 
whitilh before and reddilh behind, fixed by a violet membrane 
brown at the bafe; tail hyaline comprefled tapering. 
Abdonien without fin: tail longer than the trunk, with 
prickly lines and. terminal horizontal fin. 
Inhabits the Archipelago, Forth. fn, Arab, n. 44. 
