MEMOIRS OF THE NATIONAL ACADEMY OF SOII^NCES, 337 



GONODACTYLUS CHIKAaRA. 



There are few orders of aiii nulls of which we are more ifjiioraiit than we are of the Stomato- 

 podis. They are well known as niiiseiiin specimens, and every natural-history cabinet contains one 

 or two, which have been brought home as rare curiosities from <listant seas; but we know hardly 

 anything of the habits of the living animals. They are abundant and widely distributed, but like 

 most rapacious animals they are very alert, taking alarm at the slightest disturbance and retreat- 

 ing to the depths of their burrows at the bottom of the ocean, where they are so completely hidden 

 fiom observation that their ca[tture is difficult, and any attempt to study them in their homes is 

 almost out of the (luestiou. 



The habits of SciuilUe are tolerably well known, and iu my report on the Stomatopoda, collected 

 by II. M. S. Clinllenf/ef, I have given an account of the habits of Lysiosiiuilla based upon observa- 

 tions made at Beaufort, North Carolina; but, exce[>t for a few scattere<l and fragmentary notes in 

 the various descri[)tive papers, this is the whole of our knowledge of the order. During the sea- 

 sons of ISSfJ and 1887 I was so fortunate as to find in the Bahama Islands Oonodactylus chiragra 

 living iu localities which were peculiarly favorable for observing its habits, and I am now able to 

 supplement mj- report upon the Challenger collections by an account of this interesting species, of 

 which little had hitherto been known, except the fact that it is the most cosmopolitan of the 

 Macroma abounding on the shores and islands of all tropical and subtroi)ical seas. 



I also obtained its eggs in abundance iind succeeiled in rearing the young from them iu 

 aquaria, and am now able to make a contribution to a subject upon which there were hitherto no 

 direct observations, for it is a noteworthy fact that while the older larvtB of Stomatoi»oda have 

 long been known, and while many genera and species of them were carefully figured and described 

 and named by the older naturalists before their relationship to the adult Stomatopoda was sus- 

 pected, not a single siiecies in the whole order has, so far as I am aware, been reared from the 

 egg and in this way identified witli its specific adult. 



While the adults usually inhabit burrows in the bottom the larvae swim at the surface of the 

 ocean, and as noue of the animals which are captured in the surface uet exceed them in beauty 

 and grace, their glass-like pelagic larviie are familiar to all naturalists who have had au opi)()r- 

 tunity to study the surface fauna of the ocean. Tiieir perfect transi)arency, which permits the 

 whole of their complicated structure to be stu<lied iu the living animal, their great size and 

 rai)acity, the graceful beauty of their constant and rapiil .novements, can not fail to fascinate the 

 naturalist. Unfortunately they are as difficult to study as they are beautiful and interesting, and 

 notwithstanding their great abundance and variety, only two or three of them have been traced 

 to their adult form. 



Unlike most Malacostraca the Stomatopoda, instead of carrying their developing eggs about 

 with them, deposit them in their deep and inaccessible burrows under the water, where they are 

 aerated by the currents produced by the abdominal feet of their parents. The eggs quickly 

 perish when deprived of this constant current, and as it is very diUicult to obtain them at all, I know 

 of no Stomatopod which has ever been reared from an egg under observation. The older larvse 

 ' are hardy and are easily reared, but they are*eldom found near shore, and microscopic research 

 is so difficult at .sea that I know of only two cases in which they have been kept until they assumeil 

 the adult form. As I have stated in my rei)ort on the Challenger Stomatopoda, I have reared a 

 young Lysiosqnilla excavatrix from an old larva which was captured at the surface, and Faxon 

 has in the same way obtained the young Squilla empusa. The .young larviB are common near 

 shore, but as they seldom survive a moult in captivity they can not be identified in this way. 



The growth of the larvse is slow and the larval life long, and as they are as independent ami 

 as much exposed to changes in their environment and to the struggle for existence as the adults 

 they have undergone secondary modifications which have no reference to the life of the adult, and 

 are therefore unrepresented in the adult organism. The larvie have been arranged in genera and 

 species, but their generic characteristics are quite diflferent from those upOn which the adult genera 

 are based, and this is true in a still greater degree of their specific chara(;teristics. As thej' 

 undergo great changes during their growth different stages have been described as distinct species 

 or even genera, and it is not easy to select from the rich gatherings which are brought home by 

 S. Mis. 94 22 



