lix 



primitive band in relation to tlie 3'olk, the Hexapodous orders 

 Hymenoptera, Diptera, and certain Coleoptera (Curculionidse and 

 Donacia), and the Phr3^ganeid8e and Poduridse (genus Isotoma) 

 are ectoblasts, whilst Telephorus and the Hemiptera, with certain 

 Neuroptera (Libellulidpe and Hemerobiidffi) are endoblasts, to use 

 Dr. Dohrn's terms. The embryology of the Hemerobiidse is 

 identical with that of the Libellulidse. " What therefore," asks 

 Mr. Packard, " of the distinction between the Pseudo-Neuroptera 

 and the true Neuroptera insisted on by some of the leading 

 entomologists since Erichson's day ? Never believing that the 

 diiferences were great enough to separate the Linnean Neuroptera 

 into two independent orders or sub-orders (whichever we may 

 choose to call them), I now ask if Embryology does not give 

 independent testimony to the close alliance at least of the Libel- 

 lulidse and Hemerobiidffi, even if we go no further?" And thus 

 the position of the animal in the ovum is allowed to unite into one 

 group Libellula with its active, and Hemerobius with its necro- 

 morphous pupa ; and to separate widely Hemerobius and Phry- 

 ganea, both with inactive pupae, which are, however, furnished 

 with jaws of a structure, per se, for biting a hole in the cocoon 

 before arriving at the fully-developed imago state. I confess that 

 this specimen of classification founded upon embryological data 

 does not carry to my mind conviction of its superior worth. 



The singular form of the king crab, and its relationship, on the 

 one hand, to the Trilobites, and, on the other, to the gigantic 

 fossil Merostomata, above noticed, have given to the observations 

 which have recently been published on its development and 

 embryology a very high value. We are indebted to three inde- 

 pendent observers for a series of articles on this subject, namely, 

 ■ — 1. "The Horse Crab," by Dr. Lockwood ('American Natu- 

 ralist,' July, 1870) ; 2. " Zur Embryologie und Morphologic des 

 Limulus polyphemus," by Dr. Anton Dohrn (Jenaische Zeitschr. 

 B. vi., tab. xiv. and xv.) ; and 3, " On the Embryology of Limulus 

 polyphemus," by Dr. A. S. Packard ('American Naturalist,' vol. iv. 

 Oct. 1870). It is to the last-named gentleman that I am indebted 

 for a series of the eggs and young animals of this species, which 

 he was so good as to give me during his late visit to Oxford. A 

 succinct account of the observations contained in these three 

 memoirs is given by Mr. Woodward in the ' Quarterly Journal of 

 the Geological Society' for February, 1873. The subject of the 



