104 Mr. J. Ralfs on the Diatomacese. 



Callimome Msl, Fern. Cijaneus, antennae nigrcB, pedes cyanei fulvo-cmctij 

 tarsi flavi, alee lim<pidcE. 



Corpus sublineare, convexum, cyaneura, nitens, scitissime squameum, 



f>arce hirtum : caput transversum, breve, thoracis latitudine ; vertex sat 

 atus ; frons impressa, abrupte declivis : oculi rufi, mediocres, non extantes: 

 antennae nigrae, extrorsum crassiores, media fronte insertae, thorace paullo 

 breviores; articulus 1"' longus, gracilis, fulvus ; 2"' cyathiformis ; 3"' et 4"* 

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

 longior : thorax longiovatus : prothorax coniciis, mediocris : mesothoracis 

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

 tice approximatas ; scutellum subconicum : metathorax mediocris, declivis, 

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

 funde carinatum, thorace non longius; segmentum 1""> magnum : oviductus 

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

 aequales; trochanterespicei; genua fulva; tibiae apice fulvae ; tarsi flavi, apice 

 fusci ; protibise fulvae : alae limpidae ; squamulae 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, antennce fuscce, 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 fuscse, 

 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 suturae non bene determinatae ; scutellum 

 parvum : metathorax brevissimus : petiolus nullus : abdomen sublineare, 

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

 alas limpidae ; proalae latissimse; squamulae piceae; nervi fusci, costae dimidii 

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



July : Forest of Fontainbleau. 



XY. — On /^e Diatomacese. By John Ralfs, Esq.^ M.R.C.S., 

 Penzance*. 



[With Plates.] 

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



Tessella, Eh. 



Filaments free ; frustules irregularly separating and adhering 

 by the angles_, striated. 



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

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

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

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

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

 and from Tahellaria, as its striae are not interrupted in the centre. 

 1. T. catena, Eh. Frustules w^ith several longitudinal series of short 



* Read before the Botanical Society of Edinburgh. 



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



