14 MONOGRAPH OF BRITISH LAND AND FRESHWATER MOLLUSCA. 
Testacella scutulum G. B. Sowerby. 
1823 Testacella scutulum Sow., Gen. Shells, pl. 159. ff. 3-6. 
1826 — _ bisulcata Risso, Hist. Nat. Europe Merid., pl. 4, p. 58. 
1855 — gallopr ovineialis Gri iteloup, Dist. Geog. Limaciens, p. 15 
1855 — anglica Grat., Dist. Geog. Limae., p. 15 
1855 — hatliotidea var. se reer Mogq.-T: and., Moll: France, ii., p. 39; Jeffreys, 
Brit. Conch. 1862, p. 145, pl. 5, f. 7. 
1856 — medii-templi Panis. Zool., p. 5105. 
1S61 — fischeriana Boure., Rey. Mage. Zool. 
1861  — = peechiolii Bourg., Rev. Mag. Zool., p. 517. 
1873. — _ gestroi Issel, Ann. Mus. Civico, Genova, p. 277, ff. 
1880 — williamsiana Nevill, Proc. Zool. oe > p. LOL, pl. 13, a ile 
1838S Testacellus scutatus Lesson, Rev. Zool., i., p. 249. 
ISTORY.— 7estacellu scutulum (scutulum, a little 
} shield) was first found in a garden in Kennington 
road, Lambeth, Surrey, by Mr. G. B. Sowerby, who 
fioured and aeeeated it in his “Genera of Recent 
and Fossil Shells,” pubhshed in 1823. 
The superficial resemblance of this species to 
haliotidea, and the complete ignorance at this period 
of its striking structural pec culiarities, s soon led w 
Sowerby’s species being universally ‘regarded : 
only a slight variety of halintaden, uel 1888, tern 
the publication of Mr. Charles Ashford’s accurate 
drawings of its internal organization definitely es- 
eins tablished its specific status. 
In our English text-books, 7estacella scutulum or Testaucella haliotidea 
are indiscriminately figured as representing the latter species. Dr. Gwyn 
Jeffreys, in his “ British Conchology,” though undoubtedly representing 
T. haliotidea in vol. i., at f. 6, pl. 5, yet figures albeit roughly the shell of 
7. scutulum at f. 7, a also in the Supplement to his work. 
Lovell Reeve, in his “ British Land and Freshwater Mollusks,” gives as 
the generic figure on p. 27 a copy of Sowerby’s original figure of Testacella 
scutulum, but at p. 30, under 7. halotidea, figures an ammal which can- 
not with propriety be referred to any of our British species of Testacella, 
although the figures of the shell are good representations of those of 7. 
scutulum. 
Testacella scutulum may be regarded as linking together Tvstacella halio- 
tidea and Testacella mauge?, as, although curiously similar to 7. haliotidea 
in some external points, 1t is yet not so advanced in its internal structure, 
which in certain important respects has more affinity with that of 7. 
maugei: the south European examples approximate still more closely in 
showing fewer lateral muscles to the lingual sheath than are normally 
present in British examples. 
Diagnosis.—-7vstacella scutulum may be readily differentiated from its 
congeners when the animal is extended by the confluent origin of the 
lateral grooves, a trifle in advance of, but joined with, the peripallial fur- 
row: the usually yellow colour of the body, and the smaller shell, which is 
flat or even concave on the upper surface, with a broad, angularly concave, 
and almost truncate columella. 
Internally, it differs from Au//otidea in the absence of the flagellum to 
the penis-sheath, and from mange? by the possession of numerous lateral 
muscles to the lmeual sheath, 
