1178 



ZOOLOGICAL SOCIETY J3ULLETIN 



some of the segments or joints are wanting. In 

 tlie ancestors of the crabs the abdomen consists 

 of seven joints, as we see in the lobster or cray- 

 fish to-day. In the male especially, the abdo- 

 men is greatly reduced and very narrow and is 

 so closely a])|)lied to the under side of the 

 thorax that it lies in a groove. Tiie narrow 

 ))osterior part of tlie intestine runs througl« 

 these segments to ojien on the terminal joint 

 In the female the abdomen is much broader, for 

 the reason that it still retains the function of 

 protecting the eggs until the^- are hatched. For 

 this ))ur))ose tlie abdominal legs or swimmerets. 

 which in the crab have no other use, are well 

 adapted for carrying the eggs, which are glued 

 to them by a secretion from the oviduct just as 

 in the lobster or crayfish. 



It is interesting to note in this connection 

 that the abdomen of the immature female crab is 

 much narrower than in the adult, having a tri- 

 angular form. The swimmerets also are very 

 small and do not suggest their functions in the 

 adult. It is only with the last moult before 

 sexual maturity is reached that the broad abdo- 

 men with the large hairy, fully developed swim- 

 merets, makes its appearance. 



The eggs are very small, onl}- about l/lOO 

 of an inch in diameter and they are produced 

 in such enormous numbers that it is estimatet? 

 that a single female may lay the astonishing 

 number of 3,000,000. There seems to be no 

 very good evidence as to whether the female 

 spawns more than once. 



The newly hatched young has not the least 

 resemblance to the adult, neither in appearance 

 nor habits. It is a swimming larva, known as 

 a zoea, living at the surface of the sea. It has 

 a long a b dome n of six 

 joints, a high dorsal and | 

 lateral spines, eyes mucli 

 out of proportion to tin 

 body, and it swims by means 

 of three pairs of legs whiili 

 later become the mandibles 

 .ind maxillae. After a series 

 of moults, the zoea takes on 

 another form known .as .-i 

 megalops, from the large 

 eyes. In this condition it 

 still has little resemblance 

 to a crab, but the thoracic 

 legs are all developed and 

 the abdomen somewhat re 

 duced in proportion. The 

 eye.s at this time are mon- 

 strously large and stand out 

 at the sides of the head on 

 movable stalks. Finally af- the 



ter .-1 sutticicnt number of moults, the form li.-is 

 gradually changed .uul the li.i!)its have midcr- 

 gonc a simil.ir modification. When at last the 

 adult form is reached, the young cr.ab sinks to 

 the bottom and makes his way into shallow 

 water in protected situations along the shore, 

 where, among sea weeds or rocks, he finds his 

 food and };rows to maturitv. 



hi Intercstinc/ Fish Photor/raph. — Among 

 the wild fishes to be seen in the submarine mo- 

 tion pictures of the Williamson Expedition to 

 the IJahamas, and now on exhibition in New 

 York, is the Spotted Horse (Eques piinctatiis). 



This is a West Indian species which is known 

 ciiiefly from Cuba and Hayti. It does not ap- 

 pear from the literature at hand that this fish 

 has even been figured, and it is interesting that 

 it should have wandered within the range of 

 the camera of the first expedition to undertake 

 motion pictures under water. The pictures were 

 made in a glass-fronted photographic chamber, 

 specially constructed for this purjiose. The 

 expedition's barge with its submerged photo- 

 graphic apparatus was moved about to suitable 

 points for submarine views. Most of the pic- 

 tures were made at the Sea Gardens near Nas- 

 sau Bahamas. 



The Bulletin is indebted to the Submarine 

 Film Corporation for this enlargement from one 

 of the films. Eques puiictafiis is a handsome 

 fish with remarkably high dorsal fin. Many of 

 the fishes shown in motion are .species which 

 mav be seen at the New York Aquarium. 



C. H. T. 



si'oiTEn HOR.SK A'yrKs piwcTArrs 



