[ 311 J 



XVII I. On the Muscular and Endoskeletal Systems of Limulus and Scorpio; with 

 some Kofes on the Anatomy and Generic Characters of Scorpions. By E. Rat 

 Lankester, M.A., LL.B., F.E.S., Jodrell Professor of Zoology, assisted by 

 W. B. S. Benham and Miss E. J. Beck. 



Received and read June 19th, 1883. 



[Plates LXXII. to LXXXIII.] 



CONTENTS. 



Page 

 Part I. Introduction. By E. Ray Lankesiek 311 



,, II. Description of the Muscular and Endoskeletal Systems of Limulus. By W. B. S. Benhau. 



(Plates LXXII.-LXXVI.) 314 



„ III. Description of the lluscular and Endoskeletal Systems of Scorpio. By E. J. Beck. (Plates 



LXXVII.-LXXI5.) 339 



„ IV. Comparison of the Muscular and Endoskeletal Systems of Limulus and Scorpio, and Con- 

 sideration of the Morphological Significance of the Facts recorded. By E. Eat Lajtkestek 361 



„ V. Notes on Certain Points in the Anatomy and Generic Characters of Scorpions. By E. Rat 



Lankesiek. (Plates LXXX.-LXXXIII.) 372 



Part I. Introduction. By E. Eat Lankester. 



W HEN, two years ago, I undertook to institute a close comparison of the structure 

 of Limulus, on the one hand with that of the Crustacea, and on the other hand with 

 that of the Scorpion and other Arachnida, in order to definitely and fully substantiate 

 the view which for many years had appeared to me plausible, viz. that Limulus is no 

 Crustacean, but an Arachnid, I found considerable difficulty, owing to the fact that 

 details concerning the . structure both of Limulus and of Scorpio, in reference to many 

 critical points, were not to be met with in the literature of zoology. In consequence, I 

 have found it necessary to undertake, in conjunction with my pupils, investigations 

 upon various matters connected witli the histology and coarser anatomy of both 

 Limxdus and Scorpio, which have yielded remarkable results — remarkable because 

 they were obtained in the attempt to verify a hypothesis, and have uniformly tended to 

 verify it. Thus, I discovered in Scorpio an organ which represents the brick-red coxal 

 glands of Limulus (Proc. Roy. Soc. 1882), and in the remarkable microscopical structure 

 of these " vascular glands " I have detected a character which connects Limulus and the 

 Arachnids in the closest way whilst having no exact equivalent in any Crustacean 

 VOL. XI. — FART X. No. 1. — Mall, 18S-5.^,.*=-^^ 3 b 



