122 On a new Species of Scotopliilus. 



or of the embryos of the Nudibranchs. These two shells are 

 united at their apertures by means of a very thin membrane. 

 They have the same relations to each other and the same rela- 

 tive signification as the nauplian cuticle of the embryos of the 

 Cirripedes and the carapace of the Archizoea enclosed under 

 that cuticle. I do not think that the second shell is the origin 

 of the calcareous shell of the adult Lamellaria. I have been 

 unable to ascertain this fact by direct observation ; for the 

 nautiloid embryos, after having swum some days in the aqua- 

 riums, die without undergoing any other transformation. 



The embryogeny of Lamellaria takes considerable time for 

 its accomplishment (two or three weeks). The larvae break 

 down with great rapidity when they are removed from the 

 mucus which bathes them. Nitric acid has been of great 

 service to me in these delicate researches. 



XVI. — Description of a very large Species of Scotopliilus 

 from Western Africa. By G. E. Dobson, M.A., M.B. 



Scotopliilus gigas, n. sp. 



Ear-conch and tragus like those of S. borbonicus, Geoffr. ; 

 but the internal basal lobe of the ear is more rounded and its 

 inferior horizontal margin is straight, not in the least degree 

 concave; the upper third of the outer margin of tte conch is 

 slightly but distinctly concave ; and the tragus has the narrow 

 ridge, proceeding from the base of its inner margin across its 

 front margin, as well developed as in S. Temminckii. 



Wings to the metatarsus near the base of the toes ; last 

 two caudal vertebrae and half the third last vertebra free. 



Fur above deep chestnut, beneath yellowish white. The 

 fur on the upper surface is short and does not extend any- 

 where upon the membranes, terminating by a well-defined 

 line, and not extending posteriorly as far as the root of the 

 tail ; beneath, the wing-membrane is thinly covered as far as 

 a line drawn from the elbow to the knee-joint, and a band of 

 fur passes outwards, posterior to the forearm, to the carpus, 

 as in Vesperugo noctula. The face in front of the eyes is 

 nearly naked. 



Upper incisors with a posterior horizontal expansion of the 

 cingulum, as in S. borbonicus ; lower incisors crowded. The 

 other teeth as in S. Temminckii. 



Length (of an adult female preserved in alcohol), head 

 and body 4*6 inches, tail 2-6, tail free from membrane 0*35, 



