120 



ESSAY ON CLASSIFICATION. 



hibited ; and few types show more directly a resemblance, 

 in their early stages of growth, to the lower members of 

 their class, than the Brachyura. 



In the class of Insects, I include Myriapods, Arachnoids, 

 and the true Insects, as, according to the views expressed 

 hereafter, these natural groups constitute only different 

 degrees of complication of the same combination of or- 

 ganic systems, and must therefore be considered as natural 

 orders of one and the same class. This class, though very 

 extensively studied in a zoological and anatomical point 

 of view, and as far as the habits of its representatives are 

 concerned, still, however, requires much patient work, as 

 the early embryonic development of these animals has 

 been much less studied than their later transformations. 1 

 The type of the Arachnoids embraces two groups, the 



1 HEKOLD (M.), Entwickelungs- 

 geschichte der Schmetterliuge, etc., 

 Kassel und Marburg, 1815, 4to. fig. 

 Disquisitiones de animalium verte- 

 bris carentiurn in ovo fortnatione, 

 Frankfurt a. M., 1835, fol. fig. 

 RATHKE (H.), Entwickelungsge- 

 schichte der BUitta germanica, 

 Mcckel's Archiv, 1832. Zur Etit- 

 wickelungsgeschichte der Maul- 

 \vurfsgrille (Gryllotalpa vulgaris), 

 Miiller's Archiv, 1844, p. 27. KOL- 

 LIKER (A.), Observationes de pritna 

 Insectorum Genesi, Turici, 1842, 4to. 

 fig. ZADPACH (G.), Die Entwickel- 

 ung des Phryganiden Eies, Berlin, 

 1 vol. 4to. 1854. LEUCKABDT (R.), 

 Ueber die Micropyle und den feinern 

 Bau der Schalenhaut bei den Insek- 

 teneiern, Muller's Arch., 1855, p. 90. 

 NEWPORT (Gso.), On the Organs 

 of Reproduction and the Develop- 

 ment of Myriapoda, Phil. Trans. R. 

 Soc. 1842, II., p. 99. On the Ana- 

 tomy and Development of Meloe, 

 Ann. and Mag. Nat. Hist., 1848, vol. 

 1, p. 377, vol. 2, p. 145. STEIN 

 (FR.), Vergleichende Anatomic und 

 Physiologic der Insecten, Iste Mo- 

 nogr., Die wciblichen Geschlechts- 



organe der Kafer, Berlin, 1847, fol. 

 fig. SIEBOLD (C. TH. E. v.), Ueber 

 die Fortpflanzung vonPsyche,Zeitsch. 

 f. wiss. Zool., 1848, vol. 1, p. 93. 

 Wahre Parthenogenesis bei Schmet- 

 terlingen und Bienen, Ein Beitrag 

 zur Fortpfianzungsgeschichte der 

 Thiere, Leipzig, 1856, 8vo. ; see also 

 Ann. Sc. Nat. 4e s6r. 1856, vol. 6. 

 LEYDIG (FR.), Einige Bernerk- 

 ungen iiber die Entwickelung der 

 Blattliiuse, Zeitsch. f. wiss. Zool., 

 1850, vol. 2, p. 62. MEYER (H.), 

 Ueber die Entwickeluug des Fctt- 

 korpers, der Tracheen und der keiin- 

 bereitendenGeschlechtstheile bei den 

 Lepiclopteren, Zeitsch. f. wiss. Zool., 

 1849, vol. 1. BURNETT (W. I.), Re- 

 searches on the Development of vivi- 

 parous Aphides, Amer. Jour. Sci. and 

 Arts, 1854, vol. 17, p. 62 and 261. 

 FABRE, Recherches sur 1'anatomie 

 des organes reproducteurs et sur le 

 development des Myriapodes, Ann. 

 Sc. Nat. 4e ser. 1855, vol. 3. Etude 

 sur 1'instinct et les metamorphoses 

 des Sphegiens, Ann. Sc. Nat. 4e ser. 

 1856, vol. 6. SAUSSURE (HENRY 

 DE), Nouvelles considerations sur la 

 uidification des guepes, Ann. Sc. Nat. 



