BY H. LEIQHTON KESTEVEN. 457 



From this table it will be seen that though there is a general 

 agreement as to the number of sections, in no one point do any 

 five of these writers agree as to the values of the sections. 



Cymatium is regarded by the brothers Adams, Kobelt, and 

 Tryon as a subgenus; Fischer deemed it a section of Simpulum; 

 Melvill and Standen apparently treat it as a section of Guttiirnium; 

 whilst Dall and Simpson consider it a full genus. Such a diversity 

 of opinion can only be attributed to the imperfection of this line 

 of classification. 



The arrangement of Melvill and Standen is given in such a 

 haphazard way that it is possible I have not rightly interpreted 

 it. They regard Aquillus as the name which should be accepted 

 for the genus as a whole, and enumerate five species in the follow- 

 ing order : — 



Aquillus cheniiiitzi, Gray {=A. tranquebaricus, Lamk.) 

 ,, [Lotorium) lotoriuvi, Linn. 

 ,, {Simjndum) aquatills, Reeve. 

 ,, {Lotorium) retusus, Lamk. 

 ,, {Lotoriuin) tripus, Lamk. 



Two facts, however, are plain — (1) Lotorium, according to these 

 writers, includes forms referred by Tryon to Cymatium and 

 Gutturnium; and (2) Si7nj)ulum of Tryon is divided into two. 



I now proceed to discuss the " shuttle-cock " fate of some of the 

 species. The first species, instanced as connecting Cymatium and 

 Gutturnium (L. cynocephalum) has been referred: by Kobelt, to 

 Cymatium; by Tryon, to Gutturnium; and by Dall and Simpson, 

 to Simpulum. Ij. pyrum is referred by the brothers Adams to 

 Gutturnium, and by Tryon to Cymatium. Kobelt has placed L. 

 dunkeri in Gutturnium, whilst Tryon assigns it a place in 

 Cymatium. I have spoken of the " ^^^.02/^ "-group as connecting 

 Simjndum and Gutturnium. Watson compared his species L. 

 philomelce to L. quoyi, and yet placed it in Simpulum, from which 

 it may be concluded that he regarded the latter as referable to 

 that section also. Dall (7,226) has referred L. olearium, Linn 

 (Tryon Vj = L. costatum, Born, to Ranularia. 



