PROC. ENT. SOC. WASH., VOL. 21, NO. 6, JUNE, 1919 



With regard to the affinities of the cephids and xiphydriids, 

 Rohwer, 1915, has described a cephid genus Syntexis, which com- 

 bined characters common to the Xiphydriidae and Cephidae, 

 and he considers that the cephids are like the ancestors of the 

 xiphydriids. I have not examined the genitalia of a male of 

 Syntexis, to be able to state whether these structures would bear 

 out Rohwer 's contention concerning the ancestral nature of the 

 cephid group; but the genitalia and terminal abdominal segments 

 of the cephids which I have been able to examine, would seem to 

 indicate that the Xiphydriidae in general are less specialized 

 than the Cephidae I have seen (compare Fig. 7 with Fig. 8), in 

 so far as the copulatory apparatus is concerned; and the shape 

 of the terminal segments of the male, is a little more like that 

 of the primitive Xyelidae and "Lydidae," in the Xiphydriidae 

 (Fig. 46), than in the Cephidae (Fig. 55), although the latter fact 

 does not necessarily imply that the Xiphydriidae are more primi- 

 tive in this respect. 



So far as the terminal abdominal segments are concerned, the 

 great "breadth" (measured along the long axis of the insect's 

 body) of the eighth abdominal sternite "8 s ," and the lengthening 

 of the ninth sternite "ha" in Cephus (Fig. 55) are characters sug- 

 gestive of the condition found in the siricids (Fig. 49), as is also 

 true of the non-overlapping of the ninth and tenth tergites by 

 the eighth tergite, in these insects. The lack of cerci in the siricid 

 shown in Fig. 49 would have no bearing in such a comparison, 

 since other siricids, such as Sir ex,' etc., have well developed cerci. 

 The copulatory apparatus of Xiphydria (Fig. 20) is quite like 

 that of Sirex (Fig. 53) on the primitively ventral side (i. e., on 

 that side which is ventrally located in those insects in which a 

 torsion of the genital apparatus does not occur) ; but the copula- 

 tory apparatus of Cephus (Fig. 8) is more like that of Sirex (Fig. 

 45) on the primitively dorsal side (save for the fact that the basal 

 and terminal segments of the forceps have united to form an ap- 

 parently single segment), and the wide collar-like character of 

 the basal ring "gg" of Cephus (Fig. 8) is especially suggestive 

 of the condition occurring in the siricid group (Figs. 45, 36 and 

 37> "gg")- The terminal structures of the larvae (Figs. 47 and 

 48) are strikingly similar in the Siricidae, Cephidae, and Xiphy- 

 driidae, and it is quite possible that the Cephidae and Xiphy- 

 driidae are more closely related to the siricid group than they are 

 to the "tenthredinoid" sawflies. As far as the torsion of the 

 genital apparatus is concerned, the Siricidae, Cephidae, Xiphy- 

 driidae (Oryssidae?), Xyelidae, "Lydidae" (Megalodontidae?) 

 etc., appear to belong to the "Orthandria," or group in which 

 no torsion occurs, while all of the other forms I have examined 



