314 Bibliographical Notices. 



boscis is outermost if the individual be uppermost in the roll ; thus 

 all lie in the same direction, the proboscis outermost, as the Medusa 

 escapes, from the next left behind. When the last remains in ad- 

 hesion to the fleshy bulb, its proboscis projects outwards also. Thus 

 the under surface of the embryo is always outwards, while a portion 

 of the roll." (p. 124.) 



" Although by repeated, long, and painful observation, I have en- 

 deavoured to learn the history of the Hydra tuba and the Medusas 

 originating from it, my purpose has been but partially attained. I 

 have selected many individuals, and I have chosen colonies of both, 

 to discover whatever changes they should undergo. The hydra grew, 

 it fed, it bred, its existence was long. The Medusa lived, it neither 

 fed nor bred, its existence was infinitely shorter ; nor did it undergo 

 the smallest change from the first moment of liberation for fifty-five 

 days. Its life could not be protracted, on any occasion, beyond sixty 

 days. Between the form and habits of these two animals there is not 

 the smallest correspondence." (p. 128.) 



We pass on to take a cursory notice of our author's account of the 

 Ascidian Zoophytes. 



Plates 43 and 44 illustrate Cellularia loriculata. "The hydra is 

 minute, lively and active, almost transparent or dingy white; it 

 seldom protrudes from its dwelling, which has scarcely any percep- 

 tible margin. When doing so, twelve is the usual number of tenta- 

 cula displayed. Some have fourteen." (p. 234.) Farre says that the 

 tentacula are only ten in number. 



Cellularia reptans occupies plate 45. The hydra has twelve ten- 

 tacula. 



Cellularia fastigiata is the subject of plate 46. The hydra has six- 

 teen or eighteen tentacula. 



Cellularia ciliata forms the subject of a pretty plate, no. 47. " None 

 of the numerous tribe of Corallines can exceed the symmetry, ele- 

 gance and beauty of this interesting product waving amidst the 

 waters. The singularity of its parts and proportions seem to have 

 originated with the vigorous efforts of a sportive organic nature." 

 (p. 239.) — To the vigorous enthusiasm which dictates such a passage, 

 and there are many such in the volume, we owe the strength which 

 supported our author in his long yet unwearied labours. — The hydra 

 has from twelve to fourteen tentacula, and is remarkably vivacious. 



Cellularia avicularis is figured in plates 48 and 49. Of the latter 

 we know not what to say : it does not please us, and is useless as a 

 scientific drawing, however imposing it may look to the amateur or 

 artist. Sir John has found the species only as a parasite on the 

 Flustra truncata. " A lively ascidian hydra with fourteen, fifteen, 

 and, 1 believe, sometimes sixteen tentacula, inhabits the cells." 

 (p. 242.) 



The bird's-head processes or avicularia our author has seen on 

 Cellularia ciliata, fastigiata, avicularis, and Flustra Murrayana. The 

 obscurity which hangs over their function has not been lessened or 

 removed by his researches ; and the conjecture which he throws out 

 doubtingly that they may be parasitical seems to us altogether un- 



