FAMILY XV. LIMNIADES. 



42. Cristatella,* Cuvier. 

 Character. Polypes with about 60 tentacula, affixed with- 

 in a floating membranaceous sac, variously aggregated ; a sepa- 

 rate oriflce to each ; gevimiparous or oviparous, the ova spinife- 

 rous. 



1. C. MucEDo. Sir John Graham Dalyell. f 



Plate xliii. 

 Cristatella mucedo, Cuv. Reg. Anim. iii. 296. Gervuis 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. Bosc, Vers, iii. 180, pi. 30, fig. 



9. Stark, Elem. ii. 442 C mirabilis, Dahjell in Edin. New. Ph il. 



Joum. xvii, 414 ; and in Rep. Brit. Assoc, an. 1834, 604. 

 Hab. " An inhabitant of the fresh waters of Scotland," Sir J. G. 

 Dalyell. 



" Perfect specimens occur from six hnes 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 Hnear, 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, 

 t The author of a very interesting work on the Planariae. 



