THE EURYPTERIDA OF NEW YORK 137 
Bernard and others. Some, as Kingsley, have placed the Merostomata 
next to the Arachnida and united the two in one class. The scheme pro- 
posed by Kingsley [1894, p. 122] is as follows: 
Phylum, Arthropoda 
Subphylum I, Branchiata 
Class I, Crustacea 
Subclass 1, Trilobitae 
Subclass 2, Eucrustaceae 
Class II, Acerata | 
Subclass 1, Gigantostraca (Merostomata) 
Subclass 2, Arachnida 
Subphylum IT, Insecta 
Lankester, in his paper “ Limulus an Arachnid?” and his followers 
have gone farther and placed the Merostomata under the class Arachnida. 
They propose the following classification [see Shipley, 1909, p. 258]: 
Class, Arachnida 
Subclass 1, Delobranchiata (Merostomata) 
Order (I), Xiphosura 
Order (II), Eurypterida 
Subclass 2, Embolobranchiata 
Order (IL), Scorpionidae 
Order (II), Pedipalpi 
etc. 
The Delobranchiata, which term is equivalent to Dana’s Meros- 
tomata, are characterized by their gills which are patent and exposed; 
the Embolobranchiata have lungbooks or tracheae. We prefer to retain 
the term Merostomata, there being no apparent need for a new word. 
As there is a burning interest attaching to the question whether 
we should regard the merostomes of the Siluric as giant marine arach- 
nids or archaic crustaceans, we here briefly review the arguments for the 
relationship of the merostomes with the scorpions; and since, the larval 
