248 



the substance of the thin outer coat, giving it a very peculiar ap- 

 pearaiice. 



The sliell on the newly hatched animal, which remains as a nu- 

 cleus on the coat of the older shells, is smooth, unifornily convex, 

 without any appearance of the anterior truncation or of the radiating 

 ridges, vvhich is so peculiar iu the adult shells ; and it seems also to 

 have a straight lower edge without any appearance of the large ven- 

 tral ga})e of the genus. 



The cavitj' of the tube is contracted by an internal ring just above 

 tlie hinder end of the shells, leaving an oblong centrai aperture of 

 about half the diameter of the tube. This contraction is formed of 

 several shelly platės with interspaces between them. 



The animal has the power of repairing a fracture of the tube. 

 Theve is a specimen in the Museum which had evidently been com- 

 pletely broken across about half its length, and the direction of the 

 tube altered ; the two portions have been united by an internal irre- 

 gular white shelly coat. 



EXPLANATION OF PLATE XXXIX. 



Fig. 1. Furcella giyaniea, half the natūrai leugth ; a, b, c, d, e, the remains of 



foriner closing of the tube. 

 Fig. 2. Furcella gigantea, view of terminai closing of the tube ; of the natūrai 



size. 

 Fig. 3. Palettes, showiiigthe inner and outer sides. 

 Fig. 4. Chaną annulata, eularged. 

 Fig. 5. Chaną tettellata, enlarged. 



3. Review of the species of the Fissirostral Family Mo- 

 MOTiDiE. By Philip Lutley Sclater, M. A., F. Z. S. etc. 



(Avės, PI. CXXVIII.) 



Considerable additions have been made of late years to this rather 

 peculiar faniily of birds, of vvhich one member only was kuown to 

 Linnaeus ; and there are now at least sixteen or seventeen different 

 Motmots, of wluch examples oceur in European coUections. Two 

 or three very interesting articles have been \vritten upon the habits 

 and certain structural peculiarities of these birds ; but no modern 

 writer except Lessou, in his little-known volume, entitled ' Description 

 des Mammif eres et Oiseaux ' (where descriptions of eleven species 

 known to the author are given), has attempted a complete review of 

 the species. The following paper has been drawn up with a view to 

 meet this deficiency, and to bring together in one place short cha- 

 racters sufficient for distinguishing these birds, so as to obviate the 

 necessity of referring to all the different publications where the species 

 were origiually described. 



Latham's term MomotuSy beiug long precedent to lUiger's Prio- 

 tiites, which is sometimes employed for this group, has every claiin 

 for adoption. I therefore propose to call the group Momotidce (as 



