64 



SCIENCE. 



[N. S. Vol. XIX. No. 471. 



economic entomology, the mission of the 

 land-grant colleges and short courses. 

 E. W. Allen. 

 U. S. Depaetment op Agriculture. 



SCIENTIFIC BOOKS. 

 The Lower Devonian Fishes of Gemunden. 



By R. H. Teaquaie. Transactions of the 



Eoyal Society of Edinburgh, Vol. XL., Pt. 



4, pp. Y23-739, pis. 7, 1903. 



Dr. Traquair's recent paper will be wel- 

 comed as throwing light on Drepanaspis, one 

 of the lowliest vertebrates. In earlier papers 

 Dr. Traquair has briefly referred to this 

 armored form, known only from the lower 

 Devonian slates of Rhenish Gemiinden : in the 

 present memoir he completes his studies upon 

 it, basing them upon a remarkable series of 

 the fossil which he has collected during the 

 past dozen years. 



Gemiinden fossils, one may note incident- 

 ally, are remarkable for the great beauty with 

 which their external characters have been pre- 

 served, shown especially in mollusks, trilobites 

 and starfish; and the armored fishes have 

 proven no exceptions to the rule. The speci- 

 mens however, are always pyritized and are 

 therefore, unfortunately, valueless for histo- 

 logical study. Besides Drepanaspis, the only 

 armored fish known hitherto in detail from 

 this horizon, Traquair now describes a Coc- 

 costeus, a Phlyctmnaspis and two forms in- 

 sertce sedis. Of these the first, Oemiindina, is 

 a fish somewhat ray-like in form, character- 

 ized by a stout vertebral column and an in- 

 tegument well encrusted with shagreen den- 

 ticles. What it is no one can say, although its 

 describer regards it as ' possibly a chimasroid,' 

 admitting, however, that his idea ' rests more 

 upon feeling than upon anything else.' Un- 

 til, therefore, more and better material can be 

 secured one is constrained to conclude that 

 nothing further need be said about its affini- 

 ties. HunsriicTcia, the second problematical 

 form, is represented only by a series of ver- 

 tebral arches whose structures suggest very 

 doubtfully a pleuracanth shark. Regarding 

 Drepanaspis the paper gives many interesting 

 details, and they do not, we find, lead the 

 author to alter his earlier opinion as to the 



affinities of this form. He places it near the 

 classic Pteraspis, and regards it as the more 

 generalized, a view which will probably meet 

 general acceptance. It is a source of satis- 

 faction to students of these earliest chordates 

 that in the present form both dorsal and ven- 

 tral sides are now known with fair accuracy. 

 Desirable, none the less, is a better knowledge 

 of the region of the mouth, which is practi- 

 cally terminal, surrounded by a rather in- 

 definite series of dermal plates, and of the 

 lateral angles of the body, where possibly an 

 opercular opening is situated. And while we 

 are duly grateful to Dr. Traquair for his skil- 

 ful and continued efforts to elucidate this re- 

 markable form, we are none the less impatient 

 for further details. The object is, at the 

 best, difficult to orient, and as a symptom of 

 this it may be doubted whether the interpre- 

 tations of even an author of Dr. Traquair's 

 experience and acumen are always valid. 

 Thus, his grounds seem inadequate for dis- 

 tinguishing dorsal and ventral sides. In no 

 specimen figured is the relation of the dorsal 

 lobe of the tail .shown convincingly to be con- 

 tinuous with the so-called dorsal aspect; 

 moreover, the eyes occur on the side which 

 Traquair regards as ventral. Unless addi- 

 tional evidence is forthcoming, it would ac- 

 cordingly seem to me more probable that the 

 ' labial ' of Traquair was the ' rostral ' plate, 

 a structure which appears constant in Heter- 

 ostracans. This interpretation would permit 

 the eyes to be seen at the sides of the dorsal 

 armoring, as indeed, they occur in Pteraspis, 

 and would enable us, at the same time, to "lo- 

 cate the greater number of the larger plates 

 on the dorsal side. This conclusion is the 

 more satisfactory on comparative grounds, 

 since there is not an instance in the chor- 

 date phylum in which the eyes and the 

 most complete part of the armoring appear on 

 the (morphological) ventral side. And I 

 doubt whether, on the present evidence, we can 

 assume, with Professor Patten, that Drepan- 

 aspis might have evaded the law of vertebrate 

 orientation by swirmning on its back. Dr. 

 Traquair has attempted to solve this dorso- 

 ventral difficulty by suggesting that either the 

 orbits are ' sensory ' pits, i. e., not orbits, or 



