339] LARVAE OF THE TENTHREDINOIDEA—YUASA 21 



like dentis. In this character the larvae of this genus are more specialized 

 than all other larvae, even including Oryssus. 



Maxillae. — The maxillae (mx) are always present and typically consist 

 of cardo, stipes, subgalea, palp if er, palpus (mp), galea (gl), and lacinia 

 (la). The cardo is usually more or less chitinized and is divided into a small 

 subcardo and a larger triangular alacardo. The subcardo articulates with 

 the head in the paracoila. On the lateral margin of the alacardo the large 

 stipes is attached. The stipes is usually less chitinized than the cardo, 

 submenbranous, convex on the lateral aspect, and attached to the lateral 

 margin of the alacardo. The cephalic aspect is membranous and is con- 

 tinuous with the maxacoria. The caudal aspect along the mesal margin 

 is strongly chitinized and continuous with the elongate triangular subgalea. 

 The line of fusion is indicated by a distinct oblique chitinized ridge which 

 extends from near the proximal end of the subgalea to the lateral angle of 

 the lacinia. The latero-ventral angle of the stipes is often produced as a 

 small triangular lobe, the stipal angle of Crampton (1921) as in the 

 Tenthredininae. The palpifer is a more or less membranous, mound-like 

 lobe attached to the distal end of the cephalic margin of the stipes and 

 often bears one or more setae. The palpus is borne by the palpifer and 

 typically consists of four more or less conical segments. The relative 

 size and shape of the segments vary and afford good characters for the 

 separation of genera and species. The galea is typically strongly chitinized, 

 digit-like, conical or slightly curved mesad, bluntly pointed, unsegmented, 

 and usually smaller than the palpus. The lacinia is located mesad of the 

 galea and cephalo-ventrad of the subgalea. It is usually subtriangular, 

 slightly flattened, lobe-like, and bears a row of setae on its oblique mesal 

 margin. It is sometimes distinctly flattened, strongly chitinized, with a 

 stiff row of setae, as in the Emphytinae, or rounded and with minute spi- 

 nous setae as in Diprion, or with a sharp triangular compressed seta in 

 addition to an ordinary row of setae as in the Xyelidae. The galea and 

 lacinia are always present except in Oryssus but are reduced in size in 

 Tremex. It is interesting to note that in the leaf-miners the palpi are 

 reduced but the galea are usually normal in size and larger than the palpi. 

 In Oryssus the maxillae are fleshy lobes with all the component parts 

 obsolete and with a brownish area in which a few sensory papillae are lo- 

 cated (Rohwer and Cushman, 1917). The palpi are apparently two- 

 segmented in the Xiphydriidae and Siricidae. 



Labium. — The labium (li) consists typically of submentum, mentum, 

 stipulae, palpiger, palpi (//>), and togaglossa — representing the fused 

 glossae and paraglossae. The submentum (sm) and mentum (w) is typ- 

 ically membranous, convex, with two or more setae, and very broad in 

 the larvae of most species. In some cases, as in the Diprioninae, part 

 of the mentum is chitinized. In the leaf-miners, such as Fenusa, Metallus. 



