DE. W. B. CAEPENTEIl ON THE STRUCTURE, PHYSIOLOGY, AXD 



PLATE XXXVII. 



Fig. 1. Portion of Skeleton of Arm of Antedon rosaceus about the middle of its length, 

 seen from its dorsal aspect ; the segments of the Arms and Pinnae remaining 

 united by their ligaments ; sff, sg, syzygies. — Magnified 15 diameters. 



Fig. 2. A similar portion somewhat nearer the base, seen from its ventral aspect, 

 showing the Muscular fossae and the situation of the articulations of the Pin- 

 nules. — Magnified 10 diameters. 



Fig. 3. Basal portion of the skeleton of the Arms with their Pinnules, seen from their 

 dorsal aspect: — r', Third Radial; 1-16, Brachial segments; sg, syzygies. — 

 Magnified 10 diameters. 



Fig. 4. A similar portion of the Skeleton of the Arms with the Pinnules removed, seen 

 from their ventral aspect; showing the Interarticular Ligaments, the deep 

 Muscular fossae lying between the vertical ridges, the syzygies, sg, and the 

 articular sockets of the Pinnules, ^, ^. — Magnified 15 diameters. 



PLATE XXXVIII. 



Fig. 1. Terminal jiortion of growing Arm; from a preparation in which the soft parts 

 have been made transparent by soda, and the calcareous reticulation is shown 

 by black-ground illumination. — Magnified 120 diameters. 



Fig. 2. Portions of Armnear its termination, showing the nearly cylindrical form of its 

 segments: — c, c. Muscular Fossae; p, p. Articular sockets of Pinnules; 

 sg, syzygies.— Magnified 15 diameters. 



Fig. 3. Terminal portion of Pinnule, showing the hooks at its extremity, and the series 

 of short segments below the last two. — Magnified 70 diameters. 



Fig. 4. Terminal portion of Skeleton of Arm, with its Pinnules, seen from its dorsal 

 aspect. — Magnified 15 diameters. 



Fig. 5. Segment of Arm from about the middle of its length ; A, distal face ; B, proximal 

 face ; c, side view. — Magnified 15 diameters. 



[N.B. Figures a and B have been drawn in an inverted position with refer- 

 ence to those in Plate XXXVI. ; the upper margin being here the dorsal, and 

 the loioer the ventral']. 



Fig. 6. Portion of an Arm that has been broken at the first syzygy, with new arm 

 sprouting from this. — Magnified 10 diameters. 



Fig. 7. Single Arm growing from the Second Eadial, r"', the Third Radial being alto- 

 gether deficient. The segments of this arm have their normal size and pro- 

 portions; and the syzygies occur at their regular intervals. — Magnified 

 10 diameters. 



Fig. 8. Calyx and basal portion of Aims of a specimen which seems at A to have lost 

 one of its Rays at the junction of the First and Second Radials, a wew Ray 

 and Arms having been produced on a smaller scale ; whilst at B the Second 



