Mytilaspis, 77 



MYTILASPIS, Sign. 



Species in which the female puparium is elongated, with the pellicles at 

 the anterior extremity. Ventral scale complete, or divided down the middle ; 

 sometimes obsolete. 



Male puparium similar to that of female, but smaller and narrower ; the 

 single pellicle situated at the anterior extremity. The hinder part of the dorsal 

 scale is often marked off from the rest by a thinner transverse band which acts 

 as a hinge, allowing the extremity of the scale to be raised like a valve at the 

 emergence of the adult male. 



Adult female elongate ; abdominal segments widest, distinctly divided, often 

 expanded laterally. Circumgenital glands in five groups with comparatively 

 few orifices. Usually a few glandular pores (parastigmatic glands) round the 

 opening of the anterior spiracles. Squames tapering and spine-like. Tubular 

 spinnerets cylindrical, opening on to the margin by prominent oval pores. Anal 

 aperture situate close to base of pygidium ; genital aperture near the centre. 

 The female, after oviposition, is greatly reduced in size, occupying the anterior 

 part of the scale and almost completely covered by the pellicles. The sup- 

 plementary part of the scale acts as an ovisac. 



Adult male with the pro- and meso-thorax elongate, throwing the point of 

 insertion of the wings unusually far back. Antenna with one or more knobbed 

 hairs on the terminal joint. 



The several species of this genus are all very much alike, especially in the 

 characters of the pygidium, making their separation extremely difificult. The 

 many small differences that can be plainly seen, and appreciated as of specific 

 importance, cannot be so readily described. The structure of the ventral scale, 

 whether entire or divided, is of assistance in conjunction with other characters, 

 but cannot be entirely relied upon. The ventral scale is really structurally 

 entire in every case, the apparent division being caused by rupture in removing 

 the scale from its support ; but this always occurs along a definite line, and 

 indicates a weakness of the scale at that part which is usually constant in the 

 species. The form of the second pellicle will sometimes assist in the separation 

 of two closely allied species. 



I find in Ceylon three distinct species, and a fourth rather distinct form, 

 which is however, at present, ranked only as a variety. 



Synopsis of Ceylon Species. 



A. Ventral scale entire ; eggs arranged irregularly, or in more than two rows. 



{a) Female puparium widened behind, mussel-shaped ; ventral 



scale whitish citricola. 



{b) „ „ long and narrow, ventral scale green cocculi. 



B. Ventral scale divided ; eggs arranged in two longitudinal rows. 



(«) Female puparium red-brown ; division of ventral scale narrow gloverii. 

 (p) „ „ pale fulvous ; division of ventral scale wide pallida. 



