54 THE AMPHINEURA 
sharp and smooth. Genera—OCryptoplax, Blainville (= Chitonellus, Lam.). 
Girdle without pores. C. larvaeformis, Blainville (Fig. 26). Eastern 
Archipelago. Choneplaz, Carpenter. Girdle, with hair bundles within 
pores. C. strigatus, Sow. 
Sus-Orper 3, TELEOPLACOPHORA, Pilsbry. 
All the valves, or at least the seven anterior, with insertion plates 
cut into teeth by slits. 
Famity 6. Carronrpar, Guilding. Characters of the Sub-Order. 
Susp-Famity 1. Carronrnak. No extra-pigmental eyes ; insertion. plates 
with pectinations between the fissures. Genera—Chiton, L. Squamous 
girdle. Eudocochiton, Shuttleworth. Shaggy girdle. Trachyodon, Dall. 
Radsia, Gray. Sup-Faminy 2. Tonicimnax, Extra-pigmentar sheil eyes. 
Genera—Tonicia, Gray. Girdle smooth or shaggy (Fig. 23). 7. elegans, 
Frembly. Acanthopleura, Gould. Enoplochiton, Gray. Squamous girdle. 
E. niger, Barnes. Onithochiton, Gray. Schizochiton, Gray. Spinous girdle ; 
posterior valve notched. 8. incisus, Sow. (Fig. 28, C). Lorica, Adams. 
Loricella, Pilsbry. Liolophura, Pilsbry. 
ORDER 2. Aplacophora, von Jhering 
( = Solenogastres, Gegenbaur = Telobranchia, Koren and Danielssen 
= Scolecomorpha, Lankester). 
Our knowledge of the Aplacophora begins with Loven, who in 
1841 described the genus Chaetoderma, and with Michael Sars, who 
mentions Neomenia in 1868, under the name Solenopus, but without 
description. Chaetoderma was for a long time believed to be a 
Gephyrean worm; and Neomenia was at first included among the 
Opisthobranchiate Gastropoda in a new Order, Yelobranchia, by 
Koren and Danielssen. 
Von Jhering was the first to point out the affinities of these 
two remarkable organisms with the Chitones, and to unite them in 
the new phylum Amphineura (1876); but he classed this phylum 
with the Vermes. Gegenbaur also classed the two genera Chaeto- 
derma and Neomenia as worms under the name Solenogastres. But 
Hubrecht demonstrated the molluscan nature of the new genus Pro- 
neomenia, and its relationship to the Chitones. Lankester supported 
this view, and was followed by nearly all contemporary zoologists. 
It is generally believed that the Aplacophora are degenerate forms 
of Amphineura, derived from a chitonoid ancestor. 
Definition —The chief characteristics differentiating the Apla- 
cophora from the Polyplacophora are the following: (1) they are 
worm-like in shape; (2) the body is completely invested by the 
mantle; (3) the mantle is devoid of a shell, but bears numerous 
calcified spicula over its whole surface; (4) the digestive tract is 
straight. 
