Crangon and Galathea. 55 



on eacli branchial region ; and in Cr. rubropunctatus the median 

 gastric tooth would appear to be absent (Crangon). 

 The carinations may be represented by a single tooth, or row of 

 teeth, especially in the younger specimens ; but in the most am- 

 biguous cases examined by me, viz., in Cr. trispinosus and Cr. 

 bispinosus, careful examination detects traces of the carinas : the 

 mere number of teeth is of but little value, but their relative 

 position of the greatest. 



Thirdly, the Abdominal Somites. These may be either smooth above, the 

 telson included, or covered with carinte sulcations and spiny teeth, as 

 follows : — 



I. In iEgeon, the abdomen is generally more or less keeled, or highly 



sculptured, the telson being mostly sulcate above. 

 Cr. fasciatus. 1st to 6th somite smooth ; telson sulcate. 

 Cr. sculptus. 1st to 5th highly sculptured; 6th bicarinated ; telson 



sulcate. 

 Cr. carinicauda. Highly sculptured; 3rd to 5th highly carinated; 



gibbous; telson (?) 

 Cr. cataplir actus. 1st and 2nd spined ; 3rd and 4th carinated ; 5th 



do., and sculptured ; 6th bicarinated ; telson round. 



II. In Cheraphilus a few of the somites are carinate ; the telson is 



either deeply sulcate or carinate, as follows (carination and sulca- 

 tion are only forms of the same phenomenon) : — 



Cr. trispinosus. 6th somite obsoletely carinated ; telson sulcate. 



Cr. bispinosus. 5th and 6th somites carinated ; telson sulcate. 



Cr. intermedins. 5th carinated ; 6th sulcate ; telson not described. 



Cr. bidentatus* . Somites smooth ; telson bicarinato-sulcate. 



* Crangon bidentatus, De Haan. Pedibus secundis strictis non inflexis latioribus, 3tiis et 

 dimidium tarsum tertiorum aequantibus. Thorace depresso septemcarinato carina media, bispinosa. 

 Spinis sensim desinentibus, anteriora acuta, posteriora obtusa, Latera tercarinata, carina superiora 

 apice et ultra medium inferiore apice unispinosa medio Integra. Frontis rostrum, latius quam 

 in C. vulgari apice truncatum. Abdomen Iseve pone medium repentum angustius articulo septimo 

 medio bicarinato medio sulcato. 



i2 



