SUMMAEY OF CUREENT EESEAECHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(PEINCIPALLY mVERTEBEATA AND CRYPTOGAMIA), 



MICROSCOPY, Etc.* 



ZOOLOGY. 

 VERTEBRATA. 



a. Embryologry. f 



Development of Symbranchus marmoratus.J — Monica Taylor has 

 studied the development of this eel-like fish (from the Gran Chaco), 

 which spends a considerable part of the year buried in the mud like a 

 Lepidosiren. It has a very long gill-chamber, with avascular lining and 

 a median ventral opening. The egg is small, and its development is 

 typically Teleostean and rapid. The larva hatches out in about seven 

 days at a tropical temperature. There is a larval rostrum (1 mm. in 

 length) which disappears before the adult stage is reached. As Agar 

 discovered, the larva has pectoral fins. The shoulder-girdle persists in 

 the adult. The pectoral fins develop early and rapidly, reach their 

 maximum size seven or eight days after hatching, and fall off when the 

 creature is ten days old. They are mainly respiratory organs, and 

 possess a rich network of capillaries. The estat3lishment of perfect 

 branchial respiration is coincident with the falling oft' of the fins. Xo 

 trace of pelvic fins has been found. Perforated gill-slits of the Elas- 

 mobranch type do not occur in early stages, the clefts only becoming 

 perforate aftei' they are covered by the operculum. When branchial 

 respiration is just beginning, the gill-chamber opening is a single 

 crescent-shaped one ; as development proceeds, a single median ventral 

 opening results. There is a blind diverticulum in the dorsal roof of 

 the mouth behind the hyoid. 



The alimentary canal is solid at first, hollowed out secondarily, and 

 has no obvious connexion with the yolk. No air-bladder was detected. 

 The pyloric valves take the place of pyloric caeca and arise by out- 

 pushings of the intestine. The pancreas arises from a dorsal and two 



* The Society are not intended to be denoted by the editorial " we," and they 

 do not hold themselves responsible for the views of the authors of the papers 

 noted, nor for any claim to novelty or otherwise made by them. The object of 

 this part of the Journal is to present a summary of the papers as actually pub- 

 lished, and to describe and illustrate Instruments, Apparatus, etc., which are 

 either new or have not been previously described in this country. 



t This section includes not only papers relating to Embryology properly so- 

 called, but also those dealing with Evolution, Development, Reproduction, and 

 allied subjects. 



X Quart. Journ. Micr. Sci., lix. (1913) pp. 1-51 (4 i)ls. and 4 figs.). 



