FAMILY XV. LIMNIADES. 
42. Cristatella,* Cuvier. 
Character. Polypes with about 60 tentacula , affixed with- 
in a floating membranaceous sac , variously aggregated ; a sepa- 
rate orifice to each ; gemmiparous or oviparous , the ova spinife - 
rous, 
1. C. mucedo. Sir John Graham Dalyell. f 
Plate xliii. 
Cristatella mucedo, Cuv. Reg. Anim. iii. 296. Gervais in Ann. des Sc. 
Nat. part. Zool. vii. 77, n. s. Turpin in ibid. vii. 65, pi. 2 and 3, fig. 
1_7 C. vagans, Lam. Anim. s. Vert. ii. 97. 2de edit. ii. 110. Blainv. 
Actinolog. 489 and 678, pi. 85, fig. 7. Bose, Vers, iii. 180, pi. 30, fig. 
9. Stark, Elem. ii. 44-2 C. mirabilis, Daly ell in Edin. New. Phil. 
Journ. xvii, 41 4 ; and in Rep. Brit. Assoc, an. 1834, 604. 
Hah. “ An inhabitant of the fresh waters of Scotland,” Sir J . G . 
Dalyell. 
“ Perfect specimens occur from six lines to twenty-four in length, 
by two or three in breadth, of a flattened figure, fine translucent green 
colour, and fleshy consistence. Some of the shorter, tending to an 
elliptical form, may be compared to the external section of an ellip- 
soid ; but those of the largest dimensions are linear, that is, with pa- 
rallel sides and curved extremities.” — “ The middle of the upper and 
the whole of the under surface are smooth ; the former somewhat 
convex, occasioned by a border of 70 or 80, or even of 350 individual 
polypi, disposed in a triple row. Their number depends entirely on 
the size of the specimen, — increasing as long as it grows.” 
“ This product is endowed with the faculty of locomotion, either 
extremity indifferently being in advance, but its progression, uncom- 
monly slow, seldom exceeds an inch in twelve or twenty -four hours. 
Each of the numerous polypi, though an integral portion of the com- 
mon mass, is a distinct animal, endowed with separate action and sen- 
sation. The body, rising about a line by a tubular fleshy stem, is 
crowned by a head which may be circumscribed by a circle as much 
* The diminitive of cristata — crested. 
•f The author of a very interesting work on the Planariae. 
