104 Mr. J. Ralfs on the Diatomacese. 



Callimome JEa, Fem. Cyaneus, antennce nigrce, pedes cyanei fidvo-cincti, 

 tarsi flavi, ales limpidce. 



Corpus sublineare, convexum, cyaneum, niteiis, scitissime squameuni, 

 parce hirtum : caput transversum, breve, thoracis latitudine ; vertex sat 

 latus ; frons inipressa, abrupte declivis : oculi rufi, mediocres, non extantes : 

 antennae nigrs", extrorsum crassiores, media fronte insertge, tliorace paullo 

 breviores; articulus 1"' longus, gracilis, fulvus ; 2"' cyatbifbnnis ; o"' et 4"' 

 minimi; .5" et sequentes breves, approximati ; clava conica, articulo 10° 

 longior : thorax longiovatus : prothorax conicus, mediocris : mesothoracis 

 scutum longitudine non latius ; parapsidum suturae bene determinatae, pos- 

 tice approximatEe ; scutellum subconicum : metathorax mediocris, declivis, 

 obconicus : petiolus brevis : abdomen longiovatum, laeve, compressum, pro- 

 funda carinatum, thorace non longius; segmentum 1""' magnum : oviductus 

 exsertus ; vaginae nigrae, abdomine longiores : pedes cyanei, simplices, sub- 

 aequales; trochanterespicei; genua fulva; tibice apice fulvas ; tarsi flavi, apice 

 fusci ; protibias fulvae : alee limpidae ; squamulffi piceae ; nervi picei ; nervus 

 humeralis ulnari multo longior, radialis ulnari brevior, cubitalis brevissimus ; 

 stigma minutum. (Corp. long. lin. 2 ; alar. lin. 2.) 



Taken by E. Doubleday, Esq. near New York. 



Trichogramma Carina. Niger, antenncB fusccB, pedes picei, alee limpidce. 



Corpus nigrum, breve, depressum, nitens, laeve, parce hirtum : caput 

 transversum. brevissimum, impressum, thoracis latitudine ; vertex sat latus ; 

 frons abrupte declivis : oculi picei, mediocres, non extantes : antennae fuscae, 

 hirtae, fusiformes, thorace longiores ; articulus 1"' longus, gracilis, fusiformis; 

 2"' cyathiformis ; 3"= et sequentes ad 7"™ clavam fingentes fusiformem : tho- 

 rax ovatus : prothorax transversus, supra non conspicuus : mesothoracis scu- 

 tum longitudine latius; parapsidum suture non bene determinatae ; scutellum 

 parvum : metathorax brevissimus : petiolus nullus : abdomen sublineare, 

 thorace paullo longius vix angustius : pedes picei, simplices, subasquales : 

 alee limpidre ; proalae latissimse; squamulae piceae; nervi fusci, costae dimidii 

 vix longitudine. (Corp. long. lin. ^ ; alar. lin. ^.) 



July : Forest of Fontainbleau. 



XV. — On ^^eDiatomacea?. By John Ralfs, Esq., M.R.C.S., 

 Penzance*. 



[With Plates.] 

 [Continued from vol. xi. p. 457.] 



Tessella, Eh. 



Filaments free; frixstules irregularly separating and adhering 



by the angles, striated. 



Striatella, Tabellaria, Tetracydus and this genus form a di- 

 stinct group of the Cymbellecc, distinguished from the other ge- 

 nera by having striae on the central portion of the frustule. Tes- 

 sella differs from Striatella, as its filaments are not attached t; from 

 Tetracydus, as its frustides here and there cohere at their angles ; 

 and from Tabellaria, as its strise are not interrupted in the centre. 

 1. T. catena, Eh. Frustules with several longitudinal series of short 



* Read before the Botanical Society of Edinburgh. 



f " Stepe implexum nee affixum." — Ehrenberg, Die Inf p. 201. 



