1 88 2.J Is Limulus an Arachnid ? 



is in all Phyllopod Crustacea. Had Mr. Lankester 

 examined for himself the brain of the scorpion, he would not 

 have given the strangely incorrect account on p. 5 1 1. In the first 

 place, the nerves to the first pair of appendages arise from the 

 brain itself, as we have seen and as has been stated by other 

 authors, 1 and not as Lankester says from the oesophageal collar. 

 Moreover, as we stated, the brain is situated in the top of the 

 head of the Arachnida, and not on the same plane as the oesopha- 

 geal collar as in Limulus. In regard to the morphology (not the 

 internal structure) of the brain, Limulus much more nearly 

 approaches Apus and other Phyllopods than the scorpion and 

 other Arachnida. 



In discussing the external anatomy of Limulus, Mr. Lankester 

 claims that between the sixth abdominal segment and the spjne 

 there are six segments. We venture to suggest that four of 

 these segments are purely imaginary. Embryology, as we have 

 indicated in our figures, shows that there are but nine segments 

 in the abdomen of Limulus, the spine forming the ninth. Our 

 author speaks of the "post-anal spine," when the anus is plainly 

 situated in the base of the spine itself. It is a general law in the 

 Arthropods that the anus opens in the terminal segment of the 

 body. There are fifteen segments in the body of Limulus, as 

 embryology abundantly shows. In order to compare the body 

 of Limulus with its fifteen segments or arthromeres to that of the 

 scorpion with nineteen, Mr. Lankester conjures up four addi- 

 tional segments, which are pure metaphysical inventions. The 

 cephalothoracic plate or carapace is more than once styled a 

 "sclerite." The author here (as usual) sets aside the embryo- 

 logical proof that the carapace is composed of the tergites of six 

 segments, and allows, apparently as the results of his own inde- 

 pendent observations (as if no one had previously proved it 2 ), that 



1 Newport, whom our author quotes, expressly state- that " minu.ii.iu -]y U- 



