ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 883 



relative length seen in G. pyropalls, but tliey are always more numerous. 

 The covering of the jnipa contains air-spaces in its outer division, 

 whicli are connected with that of the inner, but as the stones or algje 

 forbid any exchange of gas with the exterior, this can only be effected 

 by the spaces in which the water is able to pass ; this exi)lains how it 

 is that we sometimes find the air-chambers on the side of the house 

 which is attached to the stone. 



Maxillary Palp of Lepidoptera.*— A. Walter has made an ex- 

 amination of the maxillary palp in one hundred and one species of 

 Lepidoptera, of which he gives careful accounts. This palp is found 

 in a series of stages of reduction, from the lowest forms of the Micro- 

 lepidoptera to the Ehopalocera ; at one end, in Micropteryx, we find 

 it with as many— six— joints as in any insects, and in Lyccena, at the 

 other end, there is no sign of it. It follows from these observations 

 that there is no number of joints which is characteristic of the whole 

 order as has been supposed by Burmeister ; on the other hand, the 

 maxillary palp has always a constant number of joints, the same 

 position and the same appendage in a given species ; there does not 

 appear to be any sexual dimorphism. On the whole, then, it is an 

 organ of considerable value in the determination of the affinities of 

 genera. 



All the lower orders of insects with which it is reasonable to 

 connect the Lepidoptera have a well-developed maxillary palp, of from 

 four to six joints. The author gives a table of the groups of Lepi- 

 doptera,^ starting with the Microlepidoptera, and showing that the 

 three-jointed Nocturna have given off forms with two joints or one ; 

 the Geometra, Sphingidaj, and Hesperidae have one. 



Development of Viviparous Aphides-t— O. Zacharias differs in 

 some pomts from Metschnikoff who in 1866 investigated the subject 

 of the development of the Aphides. Some of the errors of the earlier 

 observer are attributed to his failure to use the " method of rollinc^ " 

 by means of which we may get different aspects of the embryo. In 

 the mature embryo two retort-shaped bodies are to be seen on each 

 side, and not one as Metschnikoff reported ; the result of this dis- 

 covery is, for the first time, to bring the parts of the mouth of the 

 Aphides into homology with the corresponding organs of other insects • 

 for their retort-shaped bodies result from the modification of the 

 mandibles and maxillae. In addition to the " procephalic lobes " of 

 Huxley there is a median plate which is produced from the ventral 

 part of the cephalic hood ; the author proposes to call it the mandi- 

 bular plate; he thinks that Huxley mistook the cephalic for the 

 abdominal end of the body. The brown masses of substance which 

 in Coccus hesperidum correspond to the secondary vitellus of AjjMs 

 rosce were distinctly seen to form two long cords which open into the 

 rectum; they are the Malpighian vessels. A full memoir is 

 promised. 



* Jenaiwh. Zcitschr., xviii. (1881) pp. 121-71 



