Figure 3

3D reconstruction of the anterior end of an extended H. psammobionta (ZSM Mol-19992020/2) showing details of the central nervous system (cns). Anterior to the right. A: Dorsal view of cns. Digestive system transparent, pedal nerves omitted. A’: The reconstructed specimen prior to sectioning, box marks region shown in this figure. B: Ventral view of ganglia, digestive system, and retractor muscle. Nerves largely omitted. C: Dorsal right view of anterior cns and details of the cerebral innervation. Pedal nerves transparent. Scale bars: all 100 μm. Abbreviations: 1, double root of rhinophoral nerve; 2, presumed pleuro-pedal connective branching from ‘visceral loop’; 3, cerebropedal connective; 4, double connectives to optic ganglion; ag, accessory ganglia; apg, anterior pedal glands; bb, buccal bulb; bg, buccal ganglia; bn, buccal nerve; cpg, cerebropleural ganglion; dg, digestive gland; ey, eye; gc, bilateral ‘giant cell’ on headshield nerve; hn, headshield nerve; lag, accessory ganglia of headshield nerve; ln, labiotentacular nerve; lnag, accessory ganglia of labiotentacular nerve (more anterior); lpag, left parietal ganglion; med, medullary core of cerebropleural ganglion; mo, position of mouth opening; mu, ventral retractor muscle, note fused part between pedal and visceral ganglion; ogl, oral gland; opg, optic ganglion; opgn, nerves of optic ganglion; pg, pedal ganglion; pnd, dorsal pedal nerve; rhn, rhinophoral nerve; rnag, accessory ganglia of rhinophoral nerve (more posterior); rpag, right parietal ganglion; sc, statocyst; sgl, salivary gland; subg, subintestinal ganglion; supg, supraintestinal ganglion; vg, visceral ganglion; vn, visceral nerve(s); vl, ‘visceral loop’.