REPORT 1884. 



II. Sutured along the hack. 



1. Nuchal suture angular. 



10. Aptvchopsts, Barrande, 1872. 



1. prima, Barr. 



1A. var. secunda, now 



2. Wilsoni, II. Woodward. 

 :•>. Lapworthi, H. W. 



4. glabra, II. W. 



5. sp. nov. 



6. sp. nov. 



7. Salteri, 11. W. 



8. sp. nov 



2. Nuchal suture rounded. 



11. Peltocaris, Salter, 1863. 



1. aptychoides, Salter. 



2. ? anatina, Salter. 



3. sp. nov. 



4. sp. nov. 



5. ? Harknessi, Salter. 



3. Possibly truly Involved, without 

 a rostral piece. 



12. PiNNOCAitis,E. Ethcridgo, Jun. 1878. 



1. Lapworthi, K. E., Jr. 



Before we proceed with the comparative descriptions, we may remark 

 that some specimens of these little fossil carapaces were noticed long ago 

 by palaeontologists, before their Crustacean characters were recognised. 

 Their general likeness to the opercula of Ammonites ' led some observers 

 to suggest that these little fossils may have belonged to Goniatites, an 

 ' Ammonitidal ' cephalopod found occasionally in strata of the same forma- 

 tion (Devouian) as that in which certain of these Aptychus-like fossils 

 occur. 2 Many of the species, however, occur in beds in which Goniatites 

 are unknown. Only one specimen has as yet been found in close asso- 

 ciation with a Goniatite; 3 and nothing is yet known for certain of any 

 real opercula of Goniatites. Herr Kayser found and noticed the occurrence 

 of a ' Spathiocaris ' in the body-chamber of a Goniatites intumescens from 

 the Devonian of Nassau. Small fossils are very commonly met with in 

 a similar position in the body-chambers of Goniatites and other Cephalo- 

 pods, as also iu the cavities of various shells. 



Of the Phyllopodous forms under consideration we have some, like 

 Discinocaris, which could not, on account of their shape in general, and 

 the presence of the frontal piece in particular, have belonged to any 

 Cephalopod, much less to Goniatites, even if it possessed an operculum, 

 which is by no means proved. Next we have a large series of forms 

 which occur in beds wherein no Goniatites have been found. Lastly, as 

 is the case with specimens from Nassau, the Eifel, Hartz, and Petschora- 

 land, some occur in beds containing Goniatites, but their outlines do 

 not, even in these instances, correspond exactly with the apertures of 

 the shells of such Cephalopods. 



As other Phyllopods, such as Estheria, are imbedded in Devonian 

 rocks, it is not strange that these Phyllocarida should be there also. 



Whilst, however, we are far from denying that some forms, now 

 associated with undoubted shield-bearing Fhyllopoda, may hereafter be 

 shown to be Molluscan, we are certain that some have no relation to 

 Mollusca ; and with regard to such cases as those in which there is any 

 possibility of doubt, the oims probandi must rest with those who are dis- 

 satis6ed with and do not accept our views regarding their affinities. 



We are the more strengthened in our opinion of the affinities of these 

 palaeozoic Crustacean shields, because their ornamentation agrees Avith 

 that of known Phyllopod carapaces, both in the minute, ridge-like, con- 



1 Calcareous and bipartite, Aptyehus; corneous and undivided, Anaptychus. 



"- See, for instance, Herr Dames' remarks in the Neues Jahrb.fiir Min. &c, 1884, 

 vol. i. pp. 275-279. 



3 See Kayser, Zeitseh. d. deutseh. fjeol. Ges. xxxiv. 1S82 pp. 818, 819; and von 

 Koenen, Nines Jahrb.fiir Min. &c, 1881, vol. i. pp. 45, 4(i. 



