1 1 



lato expansus est : inferior, etiam vatidus, ad raediam alam bipartitus, sinuatim 

 inflectitur ei dilatator; membrana }»illucida setis marginalibus prrelongis 

 instructa est. 



Abdomen segruentis octo compositus, tribus basalibus, seu thoracicis, coriaceis ; 

 quinque apicalibus corneis. 



Caput subtus magnum ore deflexo, parte gulari lata. 



Prothorax prosterno (PI. XV., fig. -2, a) -at parvo; episternis minutis ; epimeris 

 parvis, receptacula coxarum postice cingentibus. Coxarum receptaeula ovalia 

 non contingentia. 



Pectus mesosterno (PL KV., fig. 2, d) Bat brevi, late carinato, margins anteriori 

 profunde excavata et utrinque acuminata, carina lata, antice sat longe et acute 

 product a : episternis humeralibus modicis ; epimeris sat magnia ad receptacula 

 coxarum extensis. Coxarum receptacula magna, ovalia, per carinam sat late 

 divisa. 

 metasterno (PI. XV., fig. 2, g) magno, Bubquadrato, ad latera corporis baud extenso, 

 margine posteriori media excavata et utrinque acuminata ; episternis angustis, 

 metasterno fere pariter longis : epimeris longis, minute triangulariter inflexis, 

 reliquis sub elytra occult i-. 



1'- at' r valde elongatus, retractilis, segruentis sex corneis conipositus, 1-5 fere pariter 

 longis, apicali caateris longiori, per totum late et profunde conice impresso, 

 apice profunde emarginato. Intra segmentum apicale, vagina cornea inclusum 

 et forsan ad natandum adhibendum, corpusculum oblongum conieum (PI. XV., 

 fig. 10) existit, ad angulum utrumque externum apgendicibus sex laminatis 

 instructum, corneis, recurvatis, ad apices tenuissimis attenuatis, internia prse- 

 longis, cseteris gradatim brevioribus atque musculorum serie propria agendis. 

 Corpusculi bujusce latera intra abdomen spatio longo suut extensa ad musculos 

 affingendos, quibus ad modum caudaa piscinas admoveri possint. 



Pedes antici coxis magnis ovalibus; trochanteribus sat magnis, triangularibus ; 

 femoribus modicis; tibiis modicis ad apices dilatatis, calcaribus validis extends 

 quatuor, interno singulo armatis: tarsis robustis, 3-articulatis, 1 et 2 brevibus, 

 3 antecedentibus ambobua duplo longiori, unguibus longis curvatis subtus ad 

 basim validisaime dilatatis atque dente magno acuto armatis. 

 int, i medii anticis similes Bed longiores et graciliores, coxis longioribus, atque 



tibiis calcaribus externis octo, interno singulo armatis. 

 postiri (PI. XV., fig. Hi coxis magnis, fere ad latera corporis extensis, per totas 

 sat late laminatis ; trochanteribus elongatis, ad apices oblique excavatis ; 

 femoribus simplicibus ; tibiis elongatis vix dilatatis, calcaribus validis externis 

 quinque interno singulo armatis, unguibus anticis similibus sed gracilioribus. 



Coxa anteriores modice distantes. 

 intermedia per carinam divisse. 

 posteriores sat remotae. 



In 18(>5 my lamented friend Mr. G. E. Crotcb first discovered tbis extraordinary 

 genus in Spain, and in 1878 he was fortunate enougb to meet with it again in 

 California. Tbe American insect proved to belong to a species distinct from its 

 European congener, and was described by Dr. Le Conte in 187-1 under tbe name of 

 Hydroscapha nutans. Tbe European species, Hydroscapha Crotchii, was shortly 

 after described by Dr. Sharp in tbe Em. Monthly Magazine. Specimens of both 

 species were subsequently sent to me for dissection, and the result of my investigation 

 convinced me that tbe genus was closely allied to the Trichopterygida. To the 

 opinion which I then expressed as to the affinity of Hydroscapha to the Tricho- 

 pterygidte I still in the main adhere, but, on account of the unilobed maxilla? of 

 Hydroscapha, consider that it should be regarded as forming a distinct family. 



I do not at all agree with the idea, lately brought forward, that the specific 

 name Gyrinoides, Aube, can be properly applied to II. Crotchii. With Limnebius, 



