244 THE AMERICAN NATURALIST. [Vor. XXXVI. 
In dealing with the arthropods we object to the violent divorcing 
of the closely allied Crustacea and arachnids by shoving the insects 
between them. The conception of a crustacean head composed of 
five segments is unwarranted, and the retention of the group Myria- 
poda, in view of the work of Pocock, is indefensible, while the 
statement (p. 193) that Limulus occurs on our Pacific coast is 
erroneous. We do not believe that ZZzx aspersa is acclimated in 
this country to the extent implied on page 198, and on page 221 the 
terms “squid” and “cuttlefish” are transposed. On page 241 there 
is an erroneous explanation of the way in which the starfish opens 
clams and mussels, and we are not inclined to accept the statement 
(p. 221) that there are over five hundred species of Unionidz in 
North America. Certainly many of the species enumerated by 
Conrad, Lea, and others are not entitled to any such rank. 
In their account of the vertebrates the authors have attempted to 
carry too far homologies between the true vertebrates and the other 
chordate forms. For instance, the anterior head cavities of the 
shark cannot be compared to the proboscis cavity of Balanoglossus ; 
and, by the way, what do the authors mean (p. 293) when they rele- 
gate the term “ Balanoglossus ” to the category of popular rather than 
generic nimes? On page 332 there is an erroneous conception of 
the pharynx, no portion of which is stomodeal; the idea of a gono- 
tome (p. 343) has been vigorously combated, and certainly, in view 
of the comparatively recent researches of Rabl, the pronephric duct 
should not be described (pp. 342, 352), without a question, as ecto- 
dermal in origin. It certainly harmonizes with some theories, but —. 
Not all Dipnoi (p. 371) have two lung sacs, while some Czecilians 
(eg., Ichthyophis) do have a ductus Botalii (p. 437). Again, it is 
certainly questionable whether Gadow's conception of the structure 
of a vertebra (p. 378) is correct; and the statements (p. 330) con- 
cerning the optic nerve need revision in the light of the results of 
Keibel, Assheton, and others, for these nerves are clearly not the 
stalks uniting the primary optic vesicles with the brain, but true 
nerves which replace them. There is also a complete crossing of 
the fibers in the lower vertebrates. The division of birds into Ratitze 
and Carinate (p. 497) should not be kept up in this year rgor. In 
view of the statement that the vertebra: of mammals *have no cup- 
and-ball articulations with one another" (p. 510), we should advise 
an examination of the cervicals of a horse, and (p- 404) would call 
attention to the fact that several amphibians have amphiccelous 
vertebrae. E LR ee 
