168 



cent., there is but o)ie apical tooth, quitc cxoeptioiially in o spe- 

 cimens froni the Straits of Calais and in one of the specimens 

 from Port Said tivo apical teeth were observed. In the lii'st of 

 these three specimens the two apical teeth that are much smaller 

 than the preceding, are of equal size and the anterior is situated 

 just midway between the apex of the rostrum and the posterior, 

 in the second the posterior apical tooth is much smaller than 

 the anterior, their position, however, is the same; in the third 

 specimen, finally, which is very young, the posterior apical tooth 

 is well developed, but the anterior is quite rudimentary and 

 only visible by means of a stroug magnifying-glass. In the adult 

 female, long 93 mm., from the Straits of Calais, with the formula 



— - — , the apical tooth is rudimentary, hardly visible. In 27 spe- 



ó 



cimens, i.e. in 56 per cent., there are five teeth on the lower 

 margin, in 17, i.e. in 35 per cent., four teeth; in the adult 

 female, long 93 mm., there are only three teeth, the 2^^ situated 

 just before the Q^^ or foremost tooth of the upper margin. In 

 the larger, ova-bearing female from Rovigno, long 105 mm., the 

 lower margin is armed with si.r well-dcveloped teeth, that reach 

 to near the extremity of the rostrum, the foremost being situated 

 just opposite the apical tooth. In the male, long 80 ram., from 

 the Straits of Calais there are only 5 teeth on the upper margin, 

 but six on the lower ; these six teeth reach to near the apical 

 tooth, but they are much smaller than usual, less prominent and 

 the 2«l is also longer than in the typical species, so that the 

 rostrum presents an abnormal appearance. In the male, finally, 



o I 1 "I 1 



from the Straits of Calais with the formula ^^ — ^^^, the 



o 



eight teeth of the lower margin reach to near the foremost tooth 

 of the upper, they are also smaller and less prominent than in 

 the typical species, the first tooth, especially, is very small; in 

 this specimen the é^^ tooth of the upper margin is abnormally 

 developed. In all the specimens two teeth are invariably placed 

 on the carapace behind the orbital margin and the third imme- 



