

808 THE MARQUIS DE FOLIN ON THE [Dec. 16, 



appearances of belonging to the family of the Caecidse. Their 

 form is very peculiar : obviously they have lost the embryonic 

 shell, and the opening thus made has been closed by a septum ; but, 

 unlike the case in Caecum, only a single decollation has taken place 

 here, leaving the shell acutely conical. On this feature the new 

 genus is founded, which I have dedicated to the Reverend Robert 

 Boog Watson. 



3. Watsonia elegans, n. sp. 



St. 186. Sept. 8, 1874. Lat. 10° 30' S., long. 142° 18' E., 

 Wednesday Island, Cape York. 8 fms. Coral-sand. Surface 

 temperature 77°'2 F. Three specimens. 



Testa adulta, tubularis, conica, leviter biarcuata, subjlava, nitida, 

 unnulis regularibus, rotundatis, valde obliquis, minimis, paulo 

 expressis, crebris, elegantissime cincta ; apertura valde obliqua, 

 annulo lato crasso valde prominente circumdata. 



Length 2'5 mm. Breadth 0"5 mm. 



This very remarkable and elegant form is extremely conical. It starts 

 with a rather regular curve, and towards the mouth bends suddenly 

 in the same direction as the very oblique aperture. It is yellowish 

 glossy and very beautifully ornamented with numerous small, trans- 

 verse, oblique rings slightly expressed, but well rounded, and though 

 close-set yet well denned. The very oblique mouth is strengthened 

 by a large and very prominent ring, which indicates the adult condition 

 of the shell. This fact of the shells being full-grown implies that 

 no further decollation was to take place, while the fineness of the 

 pointed apex indicates that only one has occurred already. The 

 septum of the apex is smooth, with a minute, scarce visible mamil- 

 lation in one specimen, which is even less marked on the second. The 

 third is broken. 



All appearances point to the Csecidse as the true position of this 

 beautiful and interesting little shell ; but even should this prove a 

 mistake, it will still constitute in any case a remarkable genus. 



s t 4. CAECUM LINEICINCTUM, n. Sp. 



St. 24. March 25, 1873. Lat. 18° 38' 30" N., long. 65° 5' 30" 

 W. Off Culebra Island, St. Thomas, Danish West Indies. 390 fms. 

 Coral-mud. One specimen. 



Testa subcylindrica, parum arcuata, albida, subopaca, sublcevis, nitida, 

 aperturam versus lineis transversis cincta. Apertura 1 Septo 

 mucronato, leviter circumdato. 



Length 2*5 mm. Breadth 0-7 mm. 



The solitary specimen of this species is in bad condition ; but the 

 shell is obviously glossy, nearly opaque, whitish and almost smooth, 

 with a few strong transverse lines like minute rings towards the 

 mouth, which is broken. The mucronated septum has possibly 

 been much larger ; for it seems eroded. Like all daqjyliform septa 

 it is surrounded by a portion of the tube which projects so as to 

 protect it. It is the first smooth or nearly smooth Caecum I have 



