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BRITISH LEPIDOPTERA. 



form — a supposition which he owns, however, wants confirmation.* He 

 adds that, in the sexual forms, males and females occur in about equal 

 numbers, the latter only laying eggs after copulation, from which 

 male and female imagines are produced ; in the parthenogenetic form 

 females only occur, which, from their structure, are capable of 

 copulation, yet, as a rule, lay fertile eggs without copulation, the eggs 

 producing only female offspring. What the offspring of a partheno- 

 genetic female paired with a sexual male would be — whether entirely 

 males or males and females, and whether such females are partheno- 

 genetic — has not been ascertained. It does not appear that the 

 parthenogenetic females must be paired at certain intervals, but that, 

 every spring, they can be paired, and hence accident plays an 

 important part. The parthenogenetic form of S. triquetrella seems to 

 be widely distributed whereas the sexual is local and confined to small 

 areas ; at Erlangen both have been observed, but at places widely 

 separated from each other. Time will show whether the observations 

 made on S. triquetrella females are peculiar, or occur in all Solenobia 

 species {Bed. Ent. Zeits., 1860, pp. 40-46). The evidence here offered 

 is not convincing and we are not prepared to accept as sufficient proof of 

 the parthenogenetic race being S. triquetrella the facts that (1) a male 

 S. triquetrella paired with a parthenogenetic female, (2) the partheno- 

 genetic females being inseparable from the sexuated females. It 

 appears to be beyond question that the female Solenobiids are almost 

 exactly similar— we have already shown (Ent. Record, xi., p. 173) that 

 a number of small differences relied upon to separate what are 

 probably $ S. lichenella from 2 S. inconspicuella would not hold 

 when living examples were examined, and hence we still feel inclined 

 to suspect that Hofmann was here dealing with two physiologically 

 distinct species — the parthenogenetic S. lichenella and the sexuated 

 S. triquetrella. It would, indeed, be remarkable if S. lichenella were a 

 parthenogenetic form of S. -pined (as generally considered on the 

 Continent) and the sexuated S. triquetrella also had a parthenogenetic 

 form. Really we know nothing yet of the subject and every student 

 must take the facts as he finds them. Besides the evidence offered by 

 Hofmann as to the possible existence of two female forms of S. trique- 

 trella, he suggests that there are two forms of 8. pineti, but the actual 

 evidence offered (Bed. Ent. Zeits., 1860, pp. 48-50) is no more satis- 

 factory than the suggestion made by Zeller (Linn. Ent., vii., p. 354). 

 He states that for six years he found, in April, on the lichen-covered 

 trunk of an old isolated pear tree, in the neighbourhood of Ratisbon, 

 cases that were very like those of 8. pineti, rather smaller, brighter 

 coloured, and with rather more prominent angles ; whilst the con- 

 tained larvae appeared to be exactly similar to those of S. pineti. From 

 these only females were reared, and these laid eggs, the larvaa hatch- 

 ing after five or six weeks. The young larvae were reared on lichen- 

 covered pieces of bark from pear and oak trees, and from these only 

 parthenogenetic females were reared. These females were scarcely 

 distinguishable from those of S. pineti, but, under the microscope, the 



* With regard to the absolute necessity for confirmation, we may call attention 

 to the fact that many good observers have considered the parthenogenetic Luffia 

 ferschaultella(pomonae) to be a female form of N. monilifera (vide, E.M.M., vi., pp. 

 91-93 ; xi., p. 208), whilst others again have considered S, lichenella and N. monilifera 

 to be interchangeable, 



