Abstract

A large, well preserved fragment of the lyssakid sponge was collected from the Middle Cambrian Marjum Formation in the House Range of western Utah. Molds of articulated spicules occur in a slab of hornfels. The specimen consists of five ranks of cruciform stauract spicules and a layer of rod-like spicules. Spicule rays form roughly rectangular quadrules, averaging 1 cm, 5 mm, 2 mm, 1 mm, and 0.5 mm for each of the five orders. Largest spicules overlie all smaller ones in regular progression. Individual spicules are composed of four gently tapering rays and each overlap adjacent spicules from one-third to two-fifths their length. Spicules were probably united by fleshy material. There is no evidence of interweaving between orders.

You do not currently have access to this article.