220 M. Julius Wagner on the 



doubt for crushing the food. Posteriorly to the gizzard the 

 gut is grey and rather broad, winding round the large brown 

 liver. The genitalia are somewhat ordinary, but rather 

 curious for their bright colour, which suggested the specific 

 name I have adopted. The albuminiparous gland and herma- 

 phrodite duct are pale ochreous yellow, as is usual, but the 

 gland has on one surface a large elongated patch of bright 

 red, which does not remain well in alcohol. The ovotestis is 

 large and irregularly globular, yellow-green in colour, with 

 two blackish broad sulci. A strong ligament has its origin 

 on the ovotestis, close to the beginning of the hermaphrodite 

 duct. 



It is perhaps this species that has sometimes been observed 

 here and taken for a true Aplysia. Gosse, in his ' Naturalists' 

 Sojourn in Jamaica,' p. b6, and Mr. E. A. Andrews, in the 

 'Johns Hopkins University Circular,' April 1892, both refer 

 to the occurrence of an AjAysia (species not identified) at 

 Jamaica. 



Institute of Jamaica, 



Kingstown, Jamaica, 



Jan. 21, 1S93. 



XXX IV. — On the Emhryology of the Mites : Segmentation of 

 the Ovuniy Origin of the Germinal Layers^ and Development 

 of the Appendages in Ixodes. By JULIUS Wagner, of St. 

 Petersburg *. 



Our knowledge of the processeswhich take place in theovumof 

 the Mites during its development is very limited. The causes 

 of this are to be found on the one hand in the small size of 

 the object, and on the other in the properties of the ovum, 

 such as the thickness of the chorion and the brittleness of the 

 yolk when hardened in alcohol, owing to the largeness of the 

 yolk-s];here3. 



Ixodes^ upon which my investigations were conducted, is a 

 com])aratively convenient subject — in the first place since its 

 development proceeds somewhat slowly, and, secondly, be- 

 cause its ova do not require any great amount of attention 

 and develop very well without especial precautions. When 

 an Ixodes has once begun to deposit its ova it no longer stirs 

 liom the spot, and takes no notice if disturbed, as is often the 



* Tianelated from the * Zoologischer Auzeiger, xv. JaLrg., no. 399 

 (August 29, 1802), pp. 316-320. 



