BRANCHIOMMA VESICULOSUM. 253 
adult just as the cephalic eye-specks of the young Hunicids disappear in the adult. The 
examples from Dinard are much less than those from Devon (De St. Joseph). 
Habits.—It is an exceedingly wary form, and when kept in confinement is chary of 
exhibiting its beautiful branchial apparatus, even the vibration caused by a foot on the floor 
causing it to withdraw with lightning-like rapidity. The ejectamenta are passed out of the 
anterior end of the tube as usual in such forms. When removed from its tube it slowly rolls 
in the vessel, elongating and contracting its body, and gently moving its branchie. 
The tube (Table CXV, fig. 2a) is leathery internally, coated externally with coarse sand 
intermixed with fragments of shells (Montagu). It is sometimes attached to stones at con- 
siderable depth as well as occurs between tide-marks in the midst of colonies of Sabella 
pemcillus (De St. Joseph). Red and other algz occasionally form tufts on it. The anterior 
end is flexible and elastic, so that it spontaneously closes and often curls up when the 
branchial fan is withdrawn. 
Claparede (1868) observes that the violet hue of the posterior region is absent in the 
Neapolitan variety, and that the eyes are proportionally much less than in B. Kollikerz. 
The ciliated ventral groove divides into two limbs, one passing between the tenth and the 
eleventh, and the other between the ninth and tenth segments to the dorsum. After fusion 
the groove attains the mid-dorsal line at the eighth seoment. Claparéde thought that the 
coarser nature of the tube in the English form might indicate specific distinction, but such 
does not appear to be the case. Finally, he is not quite sure but that his B. Kollikert may 
be a young stage of this species, and if such should be the case, it is interesting that the great 
size of the eyes is parallel to the condition common in young fishes. However, he notes 
the divergences of the collar; the absence of the branchial filaments from their special position, 
and the absence of the muciparous follicles in the “ antenne ” of B. vesiculosum as points 
requiring further consideration. Claparede (1870) found an allied species (B. vigilans) as 
a commensal on Aphrodita aculeata at Naples, its tube either lodged amongst the hairs, 
and stretching from head to anus, or between two feet not far from the posterior extremity. 
Behind the stomach the epithelium is radiate in its arrangement, arosette of long fusiform 
cells having a centre pierced with pores. 
Oerley’ (1884) gave a careful account of the structure of the skeletogenous elements 
in Branchiomma, pointing out the arrangement of the muscles, vessels, nerves and other 
parts in the branchial filaments, and the connections of the supporting tissue at the base 
of these organs. He concludes by a disquisition on the homologies of these parts with those 
of vertebrates. 
Ehlers’ (1887) describes Branchiomma bioculatum, from Florida, but as the eyes in the 
Huropean form are essentially double, a re-examination may alter the view as to the form 
being new. 
Fauvel’ (1902) describes the otocysts of this form as communicating with the exterior 
by long ciliated canals, and with cilia in the otocysts, so that the grains of quartz therein 
are in motion. , 
' «Mit. Zool. Stat. Neap.,’ Bd. v, p. 217, Taf. xii and xin, fig. 15. 
* ‘Florida Anneliden,’ p. 260, Taf. lii, figs. 1—9. 
3 “Comp. Rend. Acad. Sc. Paris,’ December 29th, 1902; and ‘Comp. Rend. Congrés internat. 
Zool. Berne, 1904, pp. 360—364, 3 text-figs. 
