JOHAN KLR. |>KC. AHcr. i:\i-. i KA.V 



\erv -trikinu de-cription of Ilir inner structure, luil -trangely enough 

 formed the conclusion. - although not without some doulil. that 

 Ihe-e remains repiv-eut lin -pines and fulcra of Axfi'i'<>lt'/>iv. Ihe plate- 

 of which. however. hav,- quite another structure. XITTKI.. in ln- 

 llniulhurh. \ul. f lll. ISS7. p. I-V -hare- tin 1 -a me view-. 



S. \Voon\\ AHD in hi- excellent work. ( lalalo^iie of Fo.--il Fi-he-". 

 i\"nl. I. l.s'.H. pat;. 126) places these remains as Tchthyodorulites and says 

 that in their character- they are nearest Orncnnflmx. These views an- 

 maintained also in his "( )ulline- of Verlehrale rahi'onlolo-x ". ds: is. p. -2\)\. 



Ill the ->;illie \e;ir. I >'. H. TR Aol'AI H ill his "Report of Ko>-j| l-'i-he- 



111 the Silurian Rock- of Scotland", which contained -o much that \\a- 

 new and fundamental, appeared \vitli (|iiite a fre.-h interpretation of 

 Psammosieus. l!v reason of his studies of the mo-t (irimitive Ostm- 

 cod<'t')tii and his investigations <! the lower Devonian Drepanaspis 

 <i<-iniin,lrni'nxix. he heheved that Ihe fraii'inentary dermal plate- which 

 had heen denoted Psammosteus, heloiii; to an ostrficinli-nu li.-h clo.-el\ 

 related to Drepanaspis. ..It is now pretty clear that PxainiHuxlrux i- 

 closel\ allied to Drepanaspis, so closely that it may he a (pie-lion as 

 to whether there i- any need for family distinction. I think, however. 

 that it i- heller for the present to keep them m -eparate families until 

 the microscopic .-Iruclure of the hard part> of Drepanaspis can he 

 investigated and more also is known regarding Ihe configuration of 

 Psammosteus and the arrangement of its plates" 1 . 



TUAOI UR'S description of rsniHin.ONfi'HN is so striking and his views 

 appear to he so \\ell founded that Ihe majority of >nhsetpient inve-lii:;,- 

 lors who have concerned thein-e|\ e> with the -v-lematic position of 

 Psammosteus have -uhscrihed to hi- hypothesis. In Ihe latest edition 

 of /irn:i.'- llandhuch. K. KOKKN has even arranged Psammostens under 

 the lamiK l>rt'i>tut(ix/ii<l<i<>. 



The pre-enl author ha- -ncceeded in studying the micro.-copic 

 -triictnre of l)rt'imnxi>ix. In this respect he is ahlo to supplement 

 TRAQUAIR'a in\f>lii;,ilion.- of this mleresliiii; form. It has heen found 

 thai the -Iruclure a-ree- ipiile closely with that of rx<nnnn>xlt>ns. and 

 the a-reemeiil j> >uc|| thai the form- inn>t have heen related. Tin- 

 matter will he further discued later on. 



< >n the ha-i- of our pre-enl knowledge it is ea>\ to decide whether 

 the remain- hefoic n- are (hose of a |ammo.-leid form. ()\\ Ihe other 

 hand il i- far more difficult lo determine how far we are justified m 



l!'|")|-| "I IM-M! li-ln-- in tin- -iliiriiin ruck- r>|' Scull.-iinl. 'rr;in-. liny. Sue. \ 

 i. -'{I. 



