498 Zoological Society. 



MONARCHA LEUCOTIS. 



Crown of the head, back of the neck, back, primaries and six middle 

 tail-feathers black ; the three lateral tail-feathers on each side black 

 with white tips ; lores, a broad mark over the eye, ear-coverts, sides 

 of the neck, scapnlaries and upper tail-coverts white ; throat white, 

 bounded below with black, the feathers lengthened and protuberant ; 

 chest and abdomen light grey ; bill and feet lead-colour. 



Total length, 5 J inches ; bill, -§■ ; wing, 2f ; tail, 2f ; tarsi, ■§-. 



Hab. Cape York, Northern Australia. 



Remark. — About the size of M. trivirgata. Specimens in the 

 British Museum. 



A Monograph of Modulus, a genus of Gasteropodous 



MOLLUSCA, OF THE FAMILY LlTTORTNID^E. By ARTHUR 



Adams, R.N., F.L.S. 



Modulus, Gray. 



Animal with the head proboscidiform, the tentacles tapering, with 

 the eyes near their distal ends. Foot small, the sides simple, without 

 lobes or filaments. Operculum thin, horny, orbicular, paucispiral. 

 Shell globose or conical, whorls nodulous ; aperture round, or qua- 

 drangular, not pearly within ; columella anteriorly with a prominent 

 lamelliform tooth ; umbilicus more or less open. 



Modulus, Gray. — Turbo, sp. Adanson — Monodonta, sp. Lamck. — 

 Monodonta, Swains. — Morulus, Reeve. 



The aperture of the shell not being pearly within, and the animal 

 being destitute of eye-peduncles, head- and foot-lobes or filaments, at 

 once distinguishes this genus from Monodonta, and removes it from 

 the family Trochidce. 



1. Modulus lenticularis, Chemnitz. 



Trochus lenticularis, Chem. Conch. 5. t. 171. f. 1665. 

 Trochus modulus, Linn. Gmel. 

 Hab. Mexico. (Mus. Cuming.) 



2. Modulus tectum, Gmel. 

 Trochus tectum, Gmel. p. 3569. no. 16. 

 Monodonta retusa, Lamck. Encyclop. 



Hab. Siquejar, Philippines ; H. C. (Mus. Cuming.) 



3. Modulus carchedonicus, Lamck. 



Monodonta carchedonicus, Lamck. Hist. An.s. Vert. torn. vii. p. 33; 

 Chem. Conch. 10. t. 165. f. 1583, 1584. 

 Monodonta Sayii, Nuttall. 

 Hab. Atooi, California ; Nuttall. (Mus. Cuming.) 



4. Modulus cidaris, Reeve. 



Morulus cidaris, Reeve, Elements of Conch, p. 141. pi. 13. f. 63. 

 Hab. St. Estivan ; H. C. (Mus. Cuming.) 



5. Modulus cerodes, A. Adams. M. testd turbinatd, umbili- 

 catd, albidd, fusco sparsim inquinatd y Icevigatd ; anfractibus 



