ANNULOSA JAVANICA. 39 
compose it, and which only again occurs in the contiguous family of Hydrophitide. They 
appear to lead naturally to Berosus, and such other genera of the next family. 
Fam. 4. HYDROPHILIDé. 
The analogy between the larger insects of this family composing the genus Hydrous and 
the larger Dytisci is too striking to escape the notice of the most cursory observer. 
Their manners, their larvee, the singular dilatation at the extremity of the anterior tarsi of their 
males may all serve to shew us how Linnezus came to uname the type of this family Dytiscus 
piceus. 
The most singular habit known of this insect is that the female spins out of her abdomen a 
gummy matter, which forms an envelope for her eggs, and these, disposed symmetrically in 
their oval receptacle, float about on the surface of the water until the larve are hatched. 
It is not known how many other genera of the family possess this curious economy. 
The insects of this family which come from tropical climates prove, by their near affinity to 
European insects, how much fewer typical forms there are of aquatic insects than of terrestrial. 
Subgenus BEROSUS. Leach. 
69. Puncneitus. B. griseo-flavescens, capite scutello thoracisque macula media divisd nigris, elytris striatis : 
maculis tribus. 
Long. corp. 3. 
Insectum supra punctulatum. Elytra maculis tribus obscuris striisque nigris impressis, interstitiis crebré 
punctatis, punctis nigricantibus. 
Oss. This genus often retains some of the metallic lustre of the Helophoride. 
Genus ENHYDRUS. Meg. 
70. Parcens. E. albicans nitidus punctulatus, thorace maculis quatuor obscurts transversé dispositis elytrisque 
obsoleté striatis. 
3 
Long. corp. sn 
Genus SPERCHEUS. Fab. 
71. Pxrarycernatus. S. infra nigricans, supra scabriusculus cinereus, elytris linets quatuor elevatis : dorso 
bituberculato, pedibus subferrugineis. 
Long. corp. 5. 
Oss. This curious little insect is truly a Spercheus, and thus becomes the second species of the 
genus that is known to entomologists. 
Genus HYDROUS. Lin. Leach. 
72. Partwrparris. H. olivaceo-niger, elytris striis punctorum tribus, margineque vagé punctulato. 
Long. corp. 14. 
Hoc Insectum ab alio Americano (H. Fuscrearrr mihi) ex Insula Sancte Trinitatis simillimo differt cor- 
pore convexiore breviore, colore dilutiore, palpis crassioribus, et antennarum articulo sexto praceden- 
tibus simul sumptis multo breviore. 
F2 73. Bilineatus. 
