. The Cambridge natural history. Zoology. 5 34 HYMENOPTERA ently a continuation of the tip of the hocly. The earlier stages are 2^assed in the lodies, or in the eggs, of other Arthropods. The Proctotrypidae is. Fig. 351.—Helorv,s anomalipes. Britain. one of the most difficult groups of Hymenoptera to define ; some of its members exhibit a great resemblance to Aculeate Hymenoptera. This is the case with the Insect we figure (Fig. 351). It, however, is an undoubted Proctotrypid, but there are other forms that approach very closely in appearance to the Acu- leata, or stinging Hymenoptera; so that
. The Cambridge natural history. Zoology. 5 34 HYMENOPTERA ently a continuation of the tip of the hocly. The earlier stages are 2^assed in the lodies, or in the eggs, of other Arthropods. The Proctotrypidae is. Fig. 351.—Helorv,s anomalipes. Britain. one of the most difficult groups of Hymenoptera to define ; some of its members exhibit a great resemblance to Aculeate Hymenoptera. This is the case with the Insect we figure (Fig. 351). It, however, is an undoubted Proctotrypid, but there are other forms that approach very closely in appearance to the Acu- leata, or stinging Hymenoptera; so that until a better comprehension is reached as to the distinction between a sting and an ovipositor the separation between Proctotry- pidae and Aculeata must be con- sidered somewhat arbitrarj-. There is extreme variety in the family; the wings differ considerably in shape and neuration; they are not infrequently altogether absent in one or both sexes. The chief distinction of the family from other parasitic Hymenoptera is the tubular form of the ovipositor; which part appears to be a continuation of the tip of the body. This latter is more definitely acuminate than usual, and has given rise to the term Oxyura, by which name the Proctotrypidae are distinguished in many books. Prom the Chalcididae they are distinguished also by the angles of the pronotuni attaining the tegulae. In this character they agree with the Cynipidae, but the ovipositor and abdomen are very different in form in these two groups, and the Proctotrypidae very frequently have a pigmented spot or stigma on the front wings which is absent in Cynipidae. As if to add to the diffi- culties the systematist meets with in dealing with this family, some of its members have the trochanters undivided, as in the case of the stinging Hymenoptera. The larvae of all that are known lead a completely parasitic life in the bodies or eggs of other Insects or of Spiders. Sometimes half a dozen specimens may find the means of sub
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