284 Mr. E. A. Smith on (he 



and Atlantic City, the hatter in the raoiitliof March. Julginj; 

 from the hopeless way in which it becomes entangled in the 

 sandbanks and shoals of a shallow coast, it would seem to hi 

 unaccustomed to such impediments, and is probably a deep- 

 water species. It is also worthy of note that the Overstran I 

 MesopJodon was within a short time of giving- birtli to a young 

 one, whereas the young of the llyperoodrn are produced in 

 the months of May and June. 



Notwithstanding the very great advance which has been 

 made in our knowledge of the Cetacea of late years, we are 

 still very ignorant with regard to the habits and distribution 

 of many species, and it is most desirable to place on record 

 every circumstance which may tend, even indirectly, to throw 

 light on a subject of so much interest. 



EXPLANATION OF PLATE XV. 



F'kj. 1. Mesoplodon bidens, ^ , seen from the left side. Scale 1 : 40. The 

 arrow a indicates the position of tJie blow-hole ; b, gular sulcus ; 

 c, eye ; d, external aiiditor}'^ meatus. 



Fly. 2. Foetus which belonged to the above specimen, seen from the left 

 and slightly from the ventral side. From a photograph taken 

 by Mr. W. D. Harmer. .Scale 1:12. b and c as above ; e, right 

 pectoral limb. 



XLVII. — Note on the Genera Geothauma and Gyrostroplia. 

 By Edgar A. Smith. 



The genus Geothauma has recently been proposed by 

 M. Crosse * for the reception of that most wonderful little 

 sliell described by Lieut. -Col. Godwin- Austen under the name 

 of OpistJiostoma grandispinosum. M. Crosse considers the 

 trochoid form, the spinous ornamentation, and the manner in 

 which the last whorl is produced upward to the top of the 

 spire of sufficient importance to distinguish it generically from 

 the typical species of Opisthostoma from India. Many of the 

 characters given in the diagnosis of the genus are specific 

 rather than generic. This may have arisen from the fact 

 that M. Crosse appears to have had but a single species in 

 view at the time. At all events, it is unsatisfactory that he 

 has not expressed his views regarding the other known species 

 of Opisthostoma from Borneo, namely 0. de Grespigniji, 

 II. Adams, 0. Wallacei, Ancey, and 0. pulchellum and 



* .To urn. de Conch. 1892, p. 282. 



