ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
33 
a. Insecta. 
Metamerism of Insect's Body.* — M. A. Lameere lias a preliminary 
notice of the results of his study of the development of Phyllodromia 
germanica. He supports the view of Savigny that the order of buccal 
appendages is, mandibles, maxillae, labium, against that of Meinert 
who puts the labium first and the mandibles last. Only four pairs of 
enterocoelic cavities are developed in that part of the embryo which 
goes to form the head ; one does not correspond to the eyes, but the 
first bears the antennae, and the succeeding the three buccal appendages. 
There is, in addition, an unpaired anterior cavity which corresponds to 
the labrum, and represents the medio-ventral chamber which causes the 
bilateral symmetry of Coelenterates. M. Lameere is led to the conclu- 
sion that there are no preoral appendages in Insects, and that, from 
every point of view, the antennas correspond to the chelicerae of 
Arachnids and the antennulas of Crustacea. In an early stage all the 
abdominal segments carry appendages, but the first and last only persist ; 
the latter forms the cerci of the adult, the former becomes of considerable 
size, and then undergoes an enlargement at its free end, becomes 
detached and falls into the amnion. As there are ten segments in the 
embryonic abdomen, three in the thorax and four in the head, the whole 
number of somites in an insect’s body is seventeen. 
Hooked Joint of Insects. f — Herr A. Ochler has a memoir on the 
hooked joint of the feet of Insects. He considers that the hooks ought 
to be regarded a3 setae modified for definite objects. The joint, in 
structure and function, belongs to one of two chief types ; there is a two- 
hooked tarsal joint with or without organs of attachment, or it is one- 
hooked. The former is divisible into three subtypes : ( a ) with an un- 
paired median fixing lobule, (6) with two outer lateral fixing lobes, 
(c) with two fixing lobes below the hooks ; the latter chief type is 
either a climbing or a clasping foot. The amount of movement pos- 
sessed by the hooks is limited, and what there is, is effected by means of 
an elastic membrane and the exterior plate. The “ extensor sole,” which 
is always present in Insects with an unpaired median fixing organ, is to 
be regarded as a modification of the extensor seta. The extensor plate 
is an organ peculiar to Insects. The fixing organs are modified out- 
growths of the integument. The tarsal margin is adapted to the func- 
tion of the hooked joint. In ectoparasitic flies the fixing lobes are well 
developed. The so-called pressure-plate of Dahl is only a movably 
articulated skeletal supporting plate for the median fixing lobule. 
Live Oak Caterpillar.^ — Writing in ‘ Zoe,’ Mr. H. H. Behr points 
out how this species (JPhryganidia californica ) is indirectly protected by 
the English sparrow ; some years ago it was thought to be a great prize 
by entomologists, but has lately become more common. Though four 
generations would arise in one summer, the live oaks on which they 
lived were not endangered, for various insectivorous birds, and especially 
a species of titmouse, ate the eggs and the caterpillars. But the sparrow, 
* Bull. Soc. Beige de Micr., xvii. (1890) pp. 2-9. 
f Arch. f. Naturgesch., lvi. (1890) pp. 221-62 (2 pis.). 
X Ainer. Natural., xxiv. (1890) pp. 6S5-6. 
1891. 
D 
