Geological Society of London. 89 



form stones ceinented ■with oxide and silicate of iron ; and 4, in 

 grains disseminated in the basalt. 



Discussion. — Mr. Roberts protested against the evolution of gaseous matter 

 being considered as a proof of meteoric origin. 



Prof. Eamsay reiterated his preyiously expressed opinion, that the masses of iron 

 might be of telluric origin. 



3. " Further Eemarks on the Eelationship of the Xipliosura to the 

 Eurypterida and to the Trilohita." By Henry Woodward, Esq., 

 F.G.S. 



In this paper the author described the recent investigations ihade 

 by Dr. A. S. Packard, Dr. Anton Dohrn, and the Eev. Samuel Lock- 

 wood, upon the developmental history of the North American King- 

 crab (Lhiulus Polyphemus), and discussed the conclusions as to 

 the alliances of the Xiphosura and Eurypterida, and the general 

 classification of the Arthropoda, to which the results of these inves- 

 tigations have led Dr. Dohrn and some other continental naturalists. 

 According to this view, the Xiphosura and Eurypterida are more 

 nearly related to certain Arachnida (the Scorpions, etc.) than to the 

 Crustacea ; and this opinion is further supported by the assertion 

 of Dr. Dohrn, that in Limulus only one pair of organs (antennules) 

 receives its nerves from the supraoesophageal ganglion, and that the 

 nature of the underlip in lAmulus differs from that prevailing 

 among the Crustacea. Dr. Dohrn also recognizes the relationship 

 of the Merostomata to the Trilobites, as shown especially by the 

 development of Limulus, and considers that the three forms [Limu- 

 lida, Eurypterida, and Triloiita) should be combined in one group 

 under the name of Gigantostraca, proposed by Hackel, and placed 

 beside the Crustacea. The author stated, on the authority of Prof. 

 Owen, that Limulus really possesses two pairs of appendages which 

 receive their nerves from the supraoesophageal ganglion ; that, 

 according to Dr. Packard, the young Limulus passes through a 

 Nauplius-stage while in the egg ; that no argument could be 

 founded upon the lower lip, the condition of which varied extremely 

 in the three groups proposed to be removed from the Crustacea ; and 

 he maintained that even from the ultra - Darwinian point of view 

 taken by Dr. Dohrn, the adoption of his proposal would be fatal to 

 the application of the hypothesis of evolution to the class Crustacea. 



Discussion. — Prof. T. Rupert Jones remarked upon the interest attaching to the 

 study of the Crustacea, and called attention to the absence of any indications of con- 

 vergence in our present knowledge of the class. He thought that, in the present day, 

 Tve must nevertheless look back to some point of convergence from which the varied 

 forms known to us may have proceeded by evolution. 



Prof. Macdonald remarked that difBculties must be expected to occur in classifica- 

 tion. He believed tbat all Invertebrate animals were to be regarded as turned upon 

 their backs, as compared with Vertebrata. The cephalic plate in Limulus he regarded 

 as the equivalent of the palate-bone. The incisive palate was very distinct in the 

 Crabs. The absence of one pair of antennae did not appear to be any reason for re- 

 moving Limulus from the Crustacea. 



Dr. Murie considered that the contemplation of the multitude of young forms re- 

 ferred to by Mr. "Woodward should serve as a warning to describers of species, and 

 also as a check to generalizations as to the number of species occurring in various 

 formations. He remarked that if we were at a point when the presence or absence of 

 a single pair of nerves could be taken as distinguishing class from class, these classes 



