226 [A.ngxi?t, 



OBSEEVATIONS ON COCCIDJE (No. 8). 

 BT ALBERT C. F. MORGAIf, T.L.S. 



Genus MYTILASPIS, Bouche. 

 1. — Mttilasbis linearis.* 



Oallinsecte de coquille, Reaumur (1738), Mem. d. Ins., t. iv, pi. t, figs. 5, 6, 7. 

 Chermes arhorum linearis, Geoffroy, Hist. Ab. d. Ins. (1764), torn, i, p. 509 ; C. 

 alietis, Sclirank, Beit. z. Naturg. (1776), 48, 5 ; C. linearis, Modeer, Act. Qoth., i, 

 22, 14 (1778) ; C. arborum, Schrank, Enum. Ins. Aust. (1781), 295, 585 ; C. conchi- 

 formis, Gmelin (1788), Syst. Nat., 2221, 37 ; C. pincti, Sclirank (1801), Fauna Boica, 

 146, 1269. Diaspis linearis, Costa (1837), Faun. Regn. Nap. (1837), Gall. Ins., 21, 

 3. Aspidiotus conchiformis, Curtis, Gardener's Chronicle (1843), p. 375, figs. 1 — -6 ; 

 Fitch, 1 and 2 Rept. Nox. Ins. (1856), p. 31 ; A.falciformis, Barensprung, Journ. 

 d'Alton et Burm. (1849) ; A. pomorum, Bouche, Ent. Zeit. (1851), p. 110 ; A. pyrns- 

 malus, Rob. Kennicott (1854), Ac. Sci. cf. Cleveland. Coccus arborum linearis. 

 Harris' Treat, on Ins. (1852), p. 220. Aspidiotus Juc/landis, Fitch, Ann. Rep. N. Y. 

 St. Ag. Soc. (1856), p. 163. Chermes conchiformis, Boisduval, Ent. Hort. (1867), p. 

 315. Mytilaspis pomicorticis, Riley, 5th Rep. St. Ent. Missouri, p. 95 ; M. abietis, 

 Signoret, Ess. s. Coeh. (1877), p. 136 ; M. conchiformis. Sign., id., p. 137, pi. vi, fig. 

 6 ; M. juglandis. Sign., id., p. 139, pi. vi, fig. 3 ; M. linearis. Sign., id., p. 140, pi. 

 vi, fig. 5 ; Doug., Ent. Mo. Mag., xxiii, p. 27 ; 31. flava. Sign., id., p. 140 ; M. po- 

 morum. Sign., id., p. 142 ; Comstock, Rep. U. S. Dept. Ag. (1880), p. 325, pi. xis, 

 fig. 2 ; id., 2nd Rep. Corn. Un. Ex. St. (1883), p. 118 ; Maskell, N. Z. Trans., xi 

 (1878), p. 192 ; N. Z. Scale Ins. (1887), p. 51 ; Doug., Ent. Mo. Mag. (1886), xxiii. 

 p. 27; M. vitis, Goethe, Jahrb. nass. Ver. Naturk., 1884; Doug., Ent. Mo. Mag., 

 xxiii, p. 28 ; M. ulicis, Doug., id., xxii, p. 249, xxiii, p. 152. 



This species, which perhaps may be considered typical of tlie genus Mytilaspis, 

 and is usually called by recent authors M. pomorum, has been considered distinct 

 from the Mytilaspis which was found on the elm by Reaumur in 1738, and which 

 was named by Geoffroy Coccus arborum linearis in 1762. Signoret observes, with, 

 reference to the three species which he describes as M. pomorum, Bouche, M. con- 

 chiformis, Gmel., and M. linearis, Geoff., " II est vrai qu'il y a si peu de difference 

 que Ton pourrait presque soutenir que les trois especes n'en font qu'une," and he 

 afterwards mentions that the distinction between the species is based on the differ- 

 ence in the number of the ventral grouped glands. But I think that a variation in 

 the number of these glands, unless accompanied by some other constant variation, 

 can scarcely be considered sufficient for specific differentiation. I received amongst 

 others nine specimens of M. pomorum from Mr. Douglas, all on one piece of Calluna 

 vulgaris, and the different individuals showed a considerable difference in the size 

 of the scale and number of grouped glands. One scale, for instance, measured '11 

 in. and another "07 in., whilst the smallest was obviously that of an adult female, as 

 it was full of eggs. One showed grouped glands, as follows : anterior 2, anterior 

 laterals 3 on one side 7 on the other, posterior laterals 7 on one side and 12 on the 

 other. Another individual had 12 in the anterior group, 17 in the anterior laterals, 

 and 14 in the posterior laterals. Mr. Maskell {op. cit., p. 53) also shows that these 

 * The references are arranged in chronological sequence. 



