1869.] MR. G. GULLIVER ON THE @SOPHAGUS OF THE AYE-AYE. 249 
These points may be determined by future observations. It will 
be noticed that the extremities of the fins and tail of the Premnas 
are attenuated to what appears to be the utmost degree consistent 
with cohesion of their molecules. 
April 22, 1869. 
The Viscount Walden, President, in the Chair. 
Mr. G. Dawson Rowley, F.Z.S., exhibited some specimens of Bri- 
tish-killed Pipits, and made the following observations upon them :— 
I have the pleasure to exhibit a series of Water-Pipits (Anthus 
aquaticus) and Rock-Pipits (Anthus obscurus), all shot or taken near 
Brighton, in spring and autumn plumage, male and female respec- 
tively, showing the distinction between the two species in the several 
states. Only two or three of the former have ever been, I think, 
noticed in print as found in the British isles, and considerable con- 
fusion has existed in collections respecting them. I have at times 
observed each one doing duty for the other. A. aquaticus is not 
very common ; but it visits the south coast regularly in the spring, 
moves on to breed, and again stops with us a few weeks on its return 
in autumn. In spring it has a blue tinge on the back, with a vinous 
one on the chest, underparts greenish; in the autumn dress these 
are lost, and the underparts turn pure white. The outer tail-feather 
also changes from buff to white. Males differ little from females. 
A communication was read from Mr. Thomas Graham Ponton, 
F.Z.S., containing a criticism of the arrangement of the shells of the 
genus Mangelia adopted by Reeve in his ‘ Monograph,’ in which it 
was pointed out that the seventy species of this group given in the 
‘Conchologia Iconica’ ought to be distributed amongst the genera 
Defrancia, Cythara, and Mangelia. Mr. Ponton gave a list of the 
species which he considered referable to each of these three genera, 
and proposed to assign one to Defrancia, fifty-three to Cythara, 
and sixteen to Mangelia. 
The following papers were read :— 
1. On the Muscular Sheath of the Cardiac End of the Cso- 
phagus of the Aye-Aye (Chiromys madagascariensis) . 
By Grorce Gutuiver, F.R.S. 
Among the many inexplicable structural arrangements of animal 
organs is that of the comparative distribution of the striped muscular 
fibre to the same part in different orders; and the obscurity is not 
