ANATOMY OF MEGAPTERA LONGIMANA. 163 



mainly to the more anterior position of the posterior nares 

 on the basis cranii, partly to the nasal bones being 1^ inch 

 shorter. 



14. ETHMO-TURBINALS. The lateral mass of the ethmoid bone 

 is more developed in Megaptera, and there are two, if not three, 

 turbinals ; in B. musculus only one turbinal, with a rudiment of 

 a second. In Megaptera the lateral mass has a height of 3 to 4 

 inches, and projects inwards for 1 to 2 inches. The meatuses 

 are (1) Not seen in a front view, but felt by the finger at the 

 back as a notch and short groove, directed horizontally forwards, 

 rather above the level of the next. (2) Seen on the anterior 

 third of the lateral mass, a groove 2 inches in length, large 

 enough to receive the little finger but wedge-shaped : from 

 below the middle of the mass, directed upwards and forwards, 

 issuing and bifurcating at the anterior pointed end of the mass. 

 Its inner edge is the turbinal, the free edge of the inner convex 

 surface of the mass. (3) An inch below the hinder end of the 

 latter begins the anterior end of the lower meatus, 1 to 1J inch 

 in width, J to J inch in depth, widening backwards for about 

 4 inches, where it is lost on the inferior surface of the mass. Its 

 inner overhanging edge is the turbinal, narrow edged, a little 

 curved, with the concavity to the meatus. 



In B. musculus there is only the meatus which appears to 

 correspond to the second of those above noted in Megaptera ; 

 but it is deeper and fissures the front of the mass so much that 

 the meatus joins the narrow space of the roof. The meatus does 

 not reach quite to the back. The turbinal is a narrow tongue 

 of the lateral mass, with a deep groove between it and the root 

 of the cavity, which, in both B. musculus and Megaptera, is 

 formed by a curved lamella reaching out from the mesethmoid. 

 In B. musculus the lateral mass is not developed anteriorly and 

 inferiorly, where No. 3 meatus occurs in Megaptera ; but at the 

 back the finger detects a notch arid short wide groove, which 

 may represent the back part of the 3rd meatus in Megaptera. 



The mesethmoid also differs here. In Megaptera it comes 

 down as a thick septum (1J inch thick above, 3 inches below) 

 nearly vertically for 2 inches and then slopes backwards, with 

 about 1 inch deep excavation ; in B. musculus, after a very short 

 median projection, it becomes deeply excavated (3J inches), the 



