154 



usually arined with four teeth, less of'ten witli tlirec and tliat in 



general one or two apical teeth occur, alniost as often two as 



one, while in adult specimens the teeth are rather rarely placed 



along the whole length of the rostrum, more often, however, in 



young individuals. The rostral teeth much resemble those of L. 



Squilla (LiNNÉ), those of the upper margin are large, splniform 



and direded obliquehj forwards ; in L. adspersus (Rathke) and its 



variety Fahricli the teeth of the upper margin are less prominent 



and have a quite different fonn. In Rathke's species the antcrior 



margin of the teeth is namely much shorter in proportion to the 



distance between the tip of the tooth and that of the preceding 



one, so that the teeth are much less prominent. 



In L. longirostris (H. M.-Edw.) the two first teeth of the upper 



margin are invariahly situated on the carapace behind the orbital 



margin, while the 3<i tooth is always placed just in front of this 



margin ; the distance between the apices of the two first teeth 



is coustantly one and a half as long as the distance between the 



2*1 and the 'M. Among the numerous specimens of the Hol- 



landsch Diep there was only one, in which the three first teeth 



were placed on the carapace, the 3^ tooth being immediately 



situated behind the orbital margin ; the rostrum of this specimen 



S -\- 2 

 was — ^^p— toothed. The 4th tooth is as far distant from the 

 4 • 



3<l as the M from the 2^, often, however, its distance from 



the 3d is a little shorter than the distance between the 2^ 



and the 3<l 5 the distances between the three or four foUow- 



ing teeth ordinarily gradually increase in length, though some- 



times the foremost tooth appears again a little shorter. The 



apical tooth or teeth are much smaller than the preceding 



and placed near the tip. The l^t tooth of the upper margin 



is a little more than twice as far distant from the posterior 



margin of the carapace than from the anterior and does not 



arise with a crest. 



The lower margin of the rostrum is deeply emarginate at the 



base, the teeth are less prominent than those of the upper margin 



