164 WALTER E. COLLINGE. 



" S. S. ' Luln/ Sept. 30th, 1875. 



" While at Natal this last time ... I also found a 

 very peculiar slug, that has puzzled me greatly. It has no 

 shield; the respiratory orifice is placed on a slight prominence 

 in the mesial line, about | in. from end of tail. The slug 

 when fully extended is about 3i in. long, and tapers gradually 

 to head, which is very small. Tentacles, two pairs, very short 

 and cylindrical ; a third pair of small colourless false tentacles, 

 formed by a prolongation of the corner of the foot. This 

 slug approaches nearer to a Testacella than anything else 

 I know, and yet it is clearly not a Testacella. I forgot to 

 mention that when reposing it brings together the margin of 

 its foot, retracts the head and turns under the tail, thus [two 

 rough figures follow] . The above is a rude sketch of the 

 slug, not very accurate, but it may enable you to find out the 

 genus to which it belongs." 



Binney^s diagnosis was (almost necessarily) very imperfect, 

 and in some features incorrect. 



In 1885 Heynemann (13) suggested the name Apera, as 

 Binney^s name indicated a false characteristic, viz. the 

 presence of a mantle lobe. This author also, as a result of an 

 examination of the external characters, suggested that the 

 genus belonged to the Testacellidie, and also gave figures 

 of this species. 



In 1892 Mr. Edgar A. Smith (29) drew attention to the 

 fact that Agassiz (1) had used the name Chlamydophorus 

 for a group of Mainmals, and that practically it was the same 

 as that employed by Binney. In this same communication he 

 described a new species, collected near to Pietermaritzburg 

 by Mr. H. C. Burnup, to which he gave the name A. burnupi. 



Prof. T. D. A. Cockerell (10) in 1893 pointed out that the 

 name Apera was pre-occupied in botany, and was of opinion 

 that Binney's name with the original spelling was preferable. 



In 1897 (4) I gave a short but very imperfect account 

 (from the condition of the material) of certain parts of the 

 anatomy of A. burnupi, with figures of the same. 



In 1900 (5) I described a further species, A. natalensis. 



