396 Mr. J. Alder on a new British Limnsea. 



this is Dot true of the whole mass, as is the case with the Mam- 

 malia. 



2. It has a tendency to exhibit the African model, but shows 

 a gi-eater conformity to the fauna of the Mascarene islands. 



3. It bears clear and characteristic traces of an affinity with 

 the Indo-Australian fauna. (Black parrots occur only in New 

 Holland and New Guinea, besides Madagascar.) 



4. The number of handsome and bright-coloured species, 

 among the birds of Madagascar, is remarkably small, considering 

 the tropical position of the island. 



XLI. — Descrijition of a new British Limnsea. 

 By Joshua Alder, Esq. 



[With a Plate.] 



The European freshwater mollusca of the pulmoniferous order 

 are so few in number, and, for the most part, so well known and 

 generally diffused, that it is only by a happy chance we meet with 

 a new species to record. It gives me pleasure therefore to be 

 able to add to the British list an undescribed Limncea lately dis- 

 covered by my friend Mr. Robert Burnett of Newcastle, in Loch 

 Skene, Dumfries-shire. 



Limnaa Burnetii. PI. XL fig. 1. 



Shell ovate, gibbous, obtuse, of a bright yellowish horn- colour, 

 rather glossy and semitransparent, delicately and pretty regu- 

 larly striated. Spire involuted and placed obliquely : the first 

 and second whorls are slightly sunk in the apex, the third rising 

 a little above them so as to be visible in profile : the body-whorl 

 is large, much -inflated, and occupies nearly the whole of the 

 shell. Aperture large and ovate ; the outer lip thin, generally 

 very regularly arched, but sometimes a little constricted in the 

 middle ; rounded at the base, and not expanded at the margin ; 

 inner lip reflected on the columella and forming a subumbilicus : 

 the columella is only very slightly twisted ; and the body- whorl, 

 which is more than usually rounded, projects a little into the 

 aperture above. The spire is not visible from the under side. 

 Length of the largest specimens three-quarters of an inch, 

 breadth rather more than half an inch. The usual size is about 

 one-third less. 



Animal of the usual form of the genus, but a little broader 

 than in L. peregra. It is dark olive-coloured, spotted with opake- 

 yellow. The cloak is nearly black, with a few paler spots. 



From its involuted spire, small specimens of this species might 



