* 



801, 



chap, xx.] EXTRA ANTENNA ARISING SEPARATELY. 521 



one (E) is inwardly directed and is as wide as, but only | the length of 

 a normal club. The posterior of the two clubs (L) is directed back- 

 wards and has only four lamellae which are apparently united together. 

 The other small club (R') is also composed of only four lamella? which 

 are similarly united together. In both L and R the middle lamellae shew 

 traces of further subdivision. The figure represents the three clubs as 

 being all in one plane, but the club R' is really below /,, which stand- 

 up from the normal antenna. It is mentioned that some of the tarsi 

 were mutilated or defective. [Here L and R' are clearly a complement- 

 ary pair, though separately arising from the normal. It will be 

 observed that as in Lereboullet's case (No. 790) the second joint, which 

 is common to two clubs, is greatly elongated.] Wesmael, Bull. Ac. 

 Belg., 1850, xvi. 2, p. 382, fig. 



Navosoma sp. (Longic.) Left antenna abnormal. The joints of 

 the normal are a little flattened from above downwards and are nearly 

 elliptical in section. But the anterior border is differentiated from the 

 posterior by the presence of two elongated patches of tissue covered 

 with sensory pores. The two patches are both on the anterior border, 

 one being* on the dorsal surface and one on the ventral, separated from 

 each other by a chitinous ridge. Upon the general surface of the 

 peripheral joints of the antennae are several other such patches, but 

 none are so distinct as those of the anterior border. The abnormal left 

 antenna has the form shewn in Fig. 1 78. So far as the 8th joint it does 



L'*R 



L'+R' 



Fig. 178. Navosoma, No. 801. Left antenna seen from below. Lettered on 

 the view that R and L' are the extra parts. S, sensory patch. (In Hope 

 Collection.) 



not differ from the normal. The 9th and 10th joints have besides their 

 chief patches of sensory pores (S) on the anterior border, an additional 

 patch (L' + R') posterior to the chief patch. But up to the 10th joint 

 there is no vertical division. The 10th joint however has two articular 

 surfaces, anterior and posterior, in the same horizontal plane. The posterior 

 bears an apical (11th) joint of normal form, having anteriorly a sensory 

 patch. But the apical joint borne by the anterior articular surface has 

 two such sensory patches, an anterior and a posterior. This joint 

 therefore contains in itself parts of a pair of joints. It is not quite 

 fully segmented off from the 10th joint. 



Nevertheless it is difficult to suppose that the anterior joint is the 

 extra pair in Secondary Symmetry, for its anterior patch, Ls, seems to 

 continue the normal series of patches, S, S, etc. Therefore the patches 

 R and L' seem to be the patches of the extra pair, though one of them 

 is on a separate joint and the other is applied to the normal. Taken 

 with the case of Odontolabis No. 799 and Mehlontha No. 800, this 



