246 MESSRS. BRADY, PARKER, AND JONES 
purposes of description ; and, in conformity with the views already expressed as to the scope 
and limitation of subdivision in a group constituted like the genus Polymorphina, there 
need be no hesitation in its adoption. It is also more in conformity with our treatment 
of the varieties in which surface-ornamentation is accepted as a ground for binomial dis- 
tinction. 
A few examples from the list of synonyms will show the relationship between the 
simple and their corresponding fistulose forms. Thus, the typical 
Polymorphina lactea becomes in its cervicorn condition P. horrida, Reuss, sp. 
P. gibba » > n P. tubulosa, D'Orb., sp. 
P. trigonula FS 5 = P. damæcornis, Reuss, sp. 
P. compressa 5 2 = P. fistulosa, Williamson. 
P. regina 5 5 i like the Crag variety figured 
Pl. XLII. fig. 38, m. 
P. fusiformis $5 5 > the long tubulose variety 
found in the Chalk. 
P. hirsuta $ » > the prickly fistulose form fi- ` 
gured by Herr von Schlicht, 
op. cit., pl. xxiv. figs. 1-3. 
and so forth. Reference to the plates will confirm and extend this analogy. 
The lobed and tubular extensions of the shell, which constitute the common character 
of the series, are never alike in two specimens, but vary in extent and shape, from minute 
excrescences resembling papille on the terminal chamber, to irregular expansions com- 
pletely investing the test. The condition most commonly found in free-growing recent 
specimens is that of tubular passages commencing at the orifice and running in the 
direction of the base of the shell. These passages are at intervals prolonged outwards, 
and form smaller tubes, which again branch and constitute what have been described as 
* stag's-horn processes” or “cauliflower excrescences.” The ends of the smaller tubuli 
are usually found open; and it is likely that they take the place, in part at least, of the 
normal terminal orifice, which is often overgrown to such an extent as to preclude the 
passage of pseudopodia. We can scarcely coincide with Dr. Carpenter’s view, that * such 
wild-growing specimens are probably always parasitic." In our experience, adherent 
examples are very rare; almost the only instances we recollect are those represented in 
the two figures, Pl. XLII. figs. 38 i, j, one recent, the other from the Crag. On the other 
hand, the most abundant gathering of fistulose specimens we have met with was from 
sand recently dredged in Berwick Bay, from which hundreds of examples might have been 
selected, not one of which bore any trace of attachment to a foreign body ; indeed the soft, 
granular nature of the material in which they lived, would of itself indicate no ground for 
this supposition. Again, those found in the Chalk appear to have been quite independent 
in their manner of growth. At the same time the specimens cited are sufficient evidence 
that the animal has the power, under favourable circumstances, of fixing or rooting itself 
by the tubular prolongations of the shell-wall. 
'The ends of the tubuli are by no means invariably open, but are often found sealed in 
