Meeting of British Associatio7i — Section C. 521 



Cyclus bilohatus, H. Woodw. Carb. L., Ireland. 



torosus, ,, „ „ 



Wrightii, „ „ „ 



Earknessi, „ ,, ,, 



radialis, Phillips, sp. „ Yorkshire, etc. 



Jonesianus, H. Woodw. ,, Ireland. 



Coal Shales, Carluke. 



{Halicyne) laxus, von Meyer. Muschelkalk, Germany. 



{Halicyne^ agnostus, ,, „ „ 



These last are doubtless either larval forms of other Crustacea, or 

 else they belong to a peculiar group, whose appearance in time has 

 been exceedingly limited. They remain for the present among the 

 unsolved problems of the palceozoologist. 



Whilst referring to the fossil Limuli, I would briefly allude to the 

 valuable contributions to the anatomy of the living Limulus, or 

 " King-Crab," of the North-east coast of North America — one by 

 my distinguished chief and colleague. Prof. Owen (published in the 

 Linnsean Transactions for this year) ; ^ the other by Prof. Alph. Milne- 

 Edwards (in the Annales des Sciences Naturelles).^ 



Limulus polyphemus of North America, and the closely allied 

 species common to the Moluccas and the coasts of China and Japan, 

 is the sole existing type of this ancient race, whose longevity as an 

 Order in time is unsurpassed among the Crustacea, save by the 

 Entomostraca alone — NeoUmulus of the Upper Silurian of Lanark 

 closely agreeing with the larval stage of the living Limulus, called 

 by Dohrn the *' Trilohiten-stadium" 



By the kindness of Prof. Owen, I am permitted to add three plates 

 from his memoir on the modem American King-crab, to illustrate 

 my Monograph on Fossil Limuli. I have also introduced (from Dr. 

 Packard's and Dr. Dohrn's works) figures of the larval stages ot 

 Limulus polyphemus, and from that of Barrande, figures of the larval 

 forms of certain Trilobites, the development of which he has traced 

 often (as in the case of Sao Jiirsuta) through more than twenty stages. 



Having read carefully the arguments of Dr. Dohrn, and subse- 

 quently the views of Dr. Packard, the elaborate papers on the 

 anatomy of Limulus by Alphonse Milne-Edwards and Prof. Owen, 

 I find nothing in these several memoirs to lead me to distrust or 

 abandon the conclusion at which I had arrived in 1866 (see Brit. 

 Assoc. Eeports, Nottingham, and Quart. Journ. Geol. Soc, 1867, 

 vol. xxiii. p. 23), as to the correctness of associating the Eurtpterida 

 and XiPHOSTJRA under the Order Merostomata, but much to confirm 

 and strengthen that conclusion. 



Prof. Owen fully concurs with my general views of the Merosto- 

 mata as an Order, although he differs from me in some minor points 

 in reference to the structure of Limulus. 



For example, he considers the anterior shield, as I do, to be the 

 cephalon, merely proposing for it the name cephaletron ; ^ whilst for 



^ Trans. Lin. Soc, 1873, vol. xxviii. pt, iii. p. 459, plates xxxvi. to xxxix. 



2 Ann. des Sc. Nat. Zoologie et Paleontologie, 1872-3, 5th series, tome xvii. 

 p. 25, plates v. to xvi. 



^ From Ke(j)a\7i, the head, and ^Tpov, a part of the abdomen, in allusion to the fact 

 that (as in other Crustacea) " a part of such cavity is associated with, the ' head ' in 



