JOHAN Kl.l.li. [SEC. ARCT. KXP. FBAM 



^Inn-hire i- unfortunately unavailable". In this all subsequent investigators 

 \\lni have dealt with this subject. are unanimous. 



I have now succeeded in obtaining the proof by reference to tin 

 microscopic structure. 1 In- latter has hren found to agree entirely on 

 the one hand with the structure of /'xtuHiiiost.rnx, and on the other to 



resemble to a great extent that of I'/i'mx/iis. In the case of the latter 

 the difference only consists in the circumstance that the vascular canal 

 -V-NMII is composed of more regular lacunes. and that the denticles are 

 \\elded together into longitudinal nhs. 



This agreement with Pternx^iilae. which is thus ajt|)arent in the 

 structure of the body plates, is even more evident when we consider the 

 form and arrangement of the hody plates. 



\\ "c ran hardly he in douhl as to how the large hody plates max 

 he identified in these two types. That side of Dn'i><utuNj>is which \\a- 

 idcntilied hy TRAQUAIR as the ventral, in the median line has -1 large 

 plates following each other. (TRAQUATR'S median ventral and mental 

 platei. At the sides we see the long cornual {dates, and in front of 

 these the 2 pierced ocular plates. These quite correspond to the plat-- 

 on the dorsal side of Pier us ins, with its median dorsal plate, rostrum. 

 two rornna and two ocular plates. On the other side, which is identified 

 hy TRAU.UAIR as the dorsal, the large oval plate which TRAQUAIR descrihed 

 a- the median dorsal plate, agrees perfectly with the large ventral plate 

 of Fteraspis. The said plate agrees in the case of the two tannin-. 

 not only m its arrangement but also in its form. The sole divergence 

 i- loimd m the short form of the rostral plate, which however is <piite 

 natural in the light of the ray-like body form of I)rc)xinaspi8. 



In consequence, it would he exceedingly remarkable if 

 the >ide> of the body, which ill the case of Ibex - o closely 

 related species are characterised by the same development 

 and arrangement of plates, should not be identical. 



' H cour>e an mve-li-ator like TR.. \.Nor.\i it ha> not overlooked tln> 

 circumstance, but neverlbele-s he arrived at the opposite conclusion. 



The most important reasons for this are >uinmed up by him in his 

 supplemental work 1 on />>v/un/^.sy>/.v as follows: 



..I submit therefore, that I have ampK shown 



! irst: That the aboral aspect of the C8.r&p8.ce oi Drepanaspis 



i- coincident \\ilb the apparent .dorsal "lobe" or aspect of the caudal tin 



Supplement In Ilir I,<>\V<T licvnnimi l''i-li.-- of Gemtinden, |i;ii:i IT: 1 .. 



