382 SUMMARY OF CURRENT RESEARCHES RELATING TO 



epidermic products, and lodge between the barbs or get into the quills. 

 They sometimes eucyst in the subcutaneous connective tissue, and are 

 occasionally found in the air-sacs. Trouessart defines four sections — 

 Pterolichefe, Analgeseae, Proctophyllodeae and Epidermopte^e —and makes 

 notes on the genera composing each. 



Life-history of Anaphia petiolata.* — Marie V. Lebour calls 

 attention to the present occurrence of larval Pycuogonids in the 

 manubrium of ^ledusoids of Obelia sp., PhMidium Jmnis2)herkum, 

 Cosmetira pilosella, and other forms. They were extremely abundant in 

 June, after that l.>ecame scarcer, and finally disappeared by October. 

 They proved to be stages of Anaphia petiolata {= Anoplo dactyl us 

 peiioJatus), which Dogiel traced from its first entry into the Obelia 

 hydro id to the older stages when it is ready to leave its host. What is 

 now shown is that many of the larv'je manage in some way to enter a 

 Medusoid. Possibly they cling to a Medusoid just as it is escaping 

 from the colony, or perhaps they may get into a gonotheca before the 

 liberation of the Medusoid. If Medusoids and Pycuogonids are left 

 together in a vessel, the Pycuogonids are attracted to the Medusoids and 

 cling to them. 



«• Crustacea. 



Autotomy in Decapod Crustaceans.t— J. Herbert Paul has continued 

 his inquiry into the process of autotomy in Decapod Crustacea. He 

 has studied the reflexes of autotomy in prawn, lobster, crayfish, hermit- 

 crabs, Galatheids, shore-crab, edible crab, spider-crab, and swimmer- 

 cralx It has been recorded by Przibram that if the leg of an Am phi pod, 

 e.g. Gamynarus, be damaged or cut, the animal at once proceeds to bite 

 the stump down to the level of the first segment. A sunilar behaviour 

 is known in Tarantula, In Decapod Crustacea this autophagy does not 

 exist as a normal reaction to injury, but it takes place under certain 

 conditions. 



The common prawn, when seized violently by a leg; extends the 

 basal segment, and by a violent tail contraction tears the limb off at the 

 free joint between the second and third segments. In the lobster and 

 crayfish the same reaction takes place, but the rupture is at the level of 

 a groove in the proximal part of the third segment. Previous to the 

 tail contraction, moreover, a flexor muscle of the thu'd segment weakens 

 the limb at the level of the groove by pulling inwards one jjart of the 

 ring of calcareous integument of the third segment central to the 

 groove. There is a definite time relation between the various elements 

 of the reflex, and autotomy can occur when the nerve-cord to the brain 

 is cut. The reflex is plurisegmental, but the part of it that causes 

 weakening of the limb at the breaking-plane is confined to one segment 

 of the nervous system. If the limb be cut cleanly off and immediately 

 freed, movements resembling autophagy in the lower forms result. 



* Jovirn. Mar. Biol. Assoc, xi. (1916) pp. 51-6 (3 figs.). 



t Proc. Eoy, Soc, Edinburgh, xxxv. (1915) pp. 232-62 (29 figs.). 



