26 Mr. W. H. Benson on a new Species of Hyalaea. 



being short as in H. angulata, is very long and. nearly perpen- 

 dicular to the plane of the shell; the lateral spines are long 

 (running out, in one specimen, to a sharp point) ; and the interior 

 of the labrum, below the insertion of the bifid rostrum, is fur- 

 nished on each side with a strong tooth, and exhibits a deep 

 fissure or sinus between the prominences. The animal presented 

 a blue or violet tint, like H. longirosiris, very difierent from the 

 hyaline, yellow, and brown colours recorded by Souleyet for that 

 of H. angulata. Taking all these characters together, it appears 

 that it cannot be regarded as a variety either of H. longirostris 

 or of H. angulata, I describe it as 



Hyalcea fissilahris, B., n. sp. 



n. testa elongato-triangulari, cornea, infra semiglobosa, antice trans- 

 versim sulcata, superne planiuscula, 5-costata, costa mediana con- 

 vexiore ; spinis lateralibus subangulatis, basin versus latis, planatis, 

 postice elongatis, ad apicem acutis, hyalinis, margine postico medio 

 angulatim prominente ; cuspide mediana posteriore lata, brevi, 

 truncata, lateraliter angulata; apertura late angulare, angusta; 

 labro subito valde inflexo, extus superne subgibboso, verticali, 

 intus dentibus 2 lateralibus prominentibus, rima profunda divisis, 

 ad insertionera rostri munito, in rostrum elongatum, subverticale, an- 

 gustum, modice aversum, intus profunde canaliculatum, ad apicem 

 bifidum, desinente. 



Long. 3^, diam. 3, alt. corporis 2, alt. labri 3 mill. 



Taken on the night of the 7th October, 1834, in N. lat. 6° 

 and W. long. 22° 25', in the same tract with the horny variety 

 of H. longirostris. 



The greater comparative length and vertical position of the 

 labrum, suddenly curved at the base, and slightly averted from 

 the shell at the termination of the beak, together with the pecu- 

 liar internal structure of the labrum, sufficiently distinguish this 

 shell from the two allied species. In H. fissirostris the promi- 

 nence at the posterior edge of the lateral spines (termed " unci- 

 nation " by Souleyet) is situated far from the point and at the 

 end of an obtuse rib at the back ; in H. longirostris it forms the 

 termination of a short narrow rib near the final process ; and in 

 H. angulata it is between the end of an obtuse rib and the ter- 

 minal spine. 



The lateral spines are altogether more horizontal, and not 

 perpendicularly curved at the outer edge as in H. longirostris. 



Hyalcea labiata, D'Orb. 



This shell first appeared in the Atlantic about 31° S. lat. and 



17^ W. long. ; again between 39° and 40° S. lat. and about 33° 



E. long. ; also in 33° S. lat. and 81° E. long., 8° S. lat. and 86° 



E. long., as far as 1° S. lat. and 89° E. long., in the Indian 



