SPIRAL ARRANGEMENTS IN ANIMALS 33 



PLATE XVI (continued) 



Fig. 9. — Stcphalia Corona (after Haeckel). Shows extraordinary spiral tentacles greatly resembling the spiral tendrils of many 

 plants. The tentacles make right and left-lianded spirals spontaneously, and as apart from stimulation or irritation of any kind. 



Fig. 10. — Hydractinia cchinata. Shows beautif\il curved spiral stems, which can be extended and withdrawn at pleasure. 



PLATE XVII 



Plate xvii. illustrates spiral formations in feathers and teeth, in the muscular arrangements of the heart, and 

 in the cast of the ventricular cavities of the heart. 



Fia. 1. — A. Exquisite spiral tail feathers of Wilson's bird of paradise {Diphyllodes wilmni) (after Guillemard). 

 B. Spiral tail feathers of lyre bird, showing beautiful double curves ("Royal Natural History"). 



Fig. 2. — Spiral teeth of Bahirusa alfurus (after Guillemard). Resemble the tusks of the mammoth and elephant in general shape 

 (see Plate xvi., Fig. 2, A and B). 



Fig. 3. — A. Dissection and photograph by the Author (1860) of the apex of the left ventricle of the lieart of the sheep. Preserved 

 in the Anatomical Museum of the University of Edinburgh. Shows beautiful right-handed symmetrical spiral whorl composed of tw(j 

 sets of muscular fibres («, h) which wind into the interior of the ventricle as indicated b)' the darts (compare with Plate xiii,. 

 Fig. 1, G). 



B. Plaster of Paris cast by the Author (1876) of the right and left ventricular cavities of the human heart. Preserved in the 

 Museum of the Royal College of Surgeons of England. Shows fine left-handed symmetrical spiral composed of two parts (a, b). In 

 this case the spiral runs from the apex to the base of the ventricles {vide darts), wliich is the opposite of A, where the spiral runs from the 

 base to the apex. Compare with spiral nebulae (Plate viii.) ; spiral flowers (Fig. 13) ; spiral seeds (Fig. 11, D, E) ; and spiral shell 

 (Plate xiii.. Fig. 1, E). 



Fig. 4. — Diagram by the Author (1859), showing that external and internal muscular fibres of the left ventricle of the heart are 

 arranged spirally, and fcirni two sets of left and two sets of right-handed spirals : that the two sets oi' external fibres whicli constitute 

 the left-handed spirals involute and enter the apex and become continuous with the two sets of internal fibres constituting the right- 

 handed spirals, which latter in turn evolute at the base and become continuous with the two sets of spiral external fibres as indicated 

 by the arrows and the numerals 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. 



PLATE XVIII 

 Plate xviii. illustrates spiral formations in the egg-purses of the shark and dog-fish, horns, and sea fan. 



Fig. 1. — A. Spiral egg-purse of Port Jackson shark {Hel&rodonius philippi). 



B. Ditto. Half natural size. 



C. Egg-purse of dog-fish (Squalitx aeanfhias). These egg-purses are provided with spiral filaments resembling the tendrils of 

 plants, by which they can fix themselves to objects in their vicinity. Like tendrils, they form double reversing spirals. 



Fig. 2. — A. Honis of eland {Oreas canna), forming typical right and left-handed spirals. These horns furnish examples of close 

 spirals, and resemble screw nails (compare with Plate cxi., Fig. 1, c). 



B. Head and horns of koodoo (Strepsiceros Kudu). The horns in this case form beautiful open right and left-handed 

 spirals similar to those seen in climbing plants. 



C. D. Skulls and spiral horns of small antelopes. Drawn by C. Beijeau from photographs by the Author. 



Fig. 3. Corkscrew sea fan {Streptoeaahis pukheriiians). Forms elegant right-handed spiral (n, h, c, d, e,f, g, h). 



PLATE XIX 



Plate xix. illustrates spiral shell formations and their resemblance to similar spiral formations in the bony 

 portions of the inner ear (human). 



Ym. 1. Examples of various shells forming elegant right and left-handed close and open spirals. 



A. Ewmpludus pentawiuJdtus (Woodward). Forms left-lianiled, close, flat spiral. 



B. Crioeeras emerici. JForms left-handed, open, flat spiral. 



0. Ecruliomphalus distans. Forms right-handed, open, flat spiral. 



D. Siliquaria anguina. Forms left-handed, semi-open, conical spiral. 



E. Shell (" phragmacone ") of Spirula fmyilis. Foinis left-handed, ojien, flat spiral. 



F. Stephanoceras (Ammonitea) humphresiamim. Forms right-handed, close, flat spiral. 



G. Axis of Ardmnedes wortheid. Forms left-handed, elongated, close spiral. From Nicholson's and Lydekker's " Palreontolngy." 



jTjQ 2. Remarkable examples of right and left-handed spirals occurring in the inner portion of the human ear. 



A Cochlea of ear laid open, a, a', Osseous wall ; b, V, lamina spiralis ; c, strands of cochlear nerve folding o-\-er at d, d'. 

 B. Osseous labyrinth of left internal ear seen from without, a, Cochlea; b, semicircular canals (after Hirschfeld and 

 Leveille). 



Pig. 3.— a. Laminae of cochlea of internal ear exposed (after Riidinger). 



Fig. 4._Bony labyrinth of right internal ear of child, a, Cochlea. The semicircular canals are seen at the left of the figur« 

 (after Riidinger), 



VOL. I, ® 



