Fig. 199.—Allolobophora chlorotica Savigny. × 4. The clitellar segments are marked in Roman numerals. t.p, Tubercula pubertatis; ♂, male pore.
Fig. 200.—Allolobophora putris Vejd. × 5. Lettering as in Fig. 199. The black dots represent the chaetae in both figures.
This is the only family of earthworms which, so far as is known, can brave the ice and snow, and what is still more difficult to understand, the perpetually frozen undersoil of the Arctic regions. Eisen has described a number of species from Spitzbergen, and Colonel Feilden recently sent me an example of Allolobophora octoedra from Kolguiev, where Mr. Trevor-Battye also saw another specimen. The family is characteristic of the Nearctic and Palaearctic regions, and though found beyond them, is probably elsewhere an accidental importation (see p. [371]). There are at least fifteen species of this family found in England and Ireland, and probably more will be identified.
There does not exist at present any comprehensive account of the British species of earthworms, though all of them are included in Dr. Rosa's recent revision of the family. Most of the British forms belong to the genus Allolobophora, which may be divided into two series according to whether the chaetae are quite close together or further apart. The extent of the clitellum and the position of those swollen eminences which appear earlier than the clitellum, and are known as tubercula pubertatis, offer further characters. In the following tables, extracted from those of Rosa, the known British species of this genus are grouped according to these three characters. With the help of these tables and Figs. 199 and 200, any of the species ought to be easily identified.
With Chaetae Distant.[[449]]
| 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | |
| A. putris | ··· | — | — | — ··· | — — | — — | — | ··· | ||||
| A. constricta | — | — | — | — | — | — | ||||||
| A. veneta | ··· | — | — | — | — — | — — | — | — | ||||
| A. octoedra | — | — | — | — — | — — | ··· | ||||||
| A. cyanea (subsp. profuga) | — | — — | — — | — — | — — | — | ||||||
| A. rubida | — — | — — | — — | — — | — — | — — | ||||||
| A. mammalis | — | — | — — | — — | — | — |
| 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | |
| A. putris | ······ | —— | —— | —— ······ | —— —— | —— —— | —— | ······ | ||||
| A. constricta | —— | —— | —— | —— | —— | —— | ||||||
| A. veneta | ······ | —— | —— | —— | —— —— | —— —— | —— | —— | ||||
| A. octoedra | —— | —— | —— | —— —— | —— —— | ······ | ||||||
| A. cyanea (subsp. profuga) | —— | —— —— | —— —— | —— —— | —— —— | —— | ||||||
| A. rubida | —— —— | —— —— | —— —— | —— —— | —— —— | —— —— | ||||||
| A. mammalis | —— | —— | —— —— | —— —— | —— | —— |
With Chaetae Paired.
| 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | |
| A. rosea | ··· | — | — | — | — | — — | — — | — ··· | — | |||||
| A. foetida | ··· | ··· | — | — | — — | — — | — — | — ··· | — | |||||
| A. eiseni | ··· | — | — | — | — | — | — | — | — | |||||
| A. caliginosa | ··· | — | — | — | — — | — ··· | — — | — | ··· | |||||
| A. terrestris | ··· | — | — | — | — | — — | — — | — — | — | |||||
| A. chlorotica | ··· | — | — | — — | — | — — | — | — — | — | — | ||||
| A. georgii | ··· | — | — | — — | — | — — | — | — |